The final version of Ubuntu 14.04 LTS is now available

The Ubuntu developers are moving quickly to bring you the absolute latest and greatest software the Open Source community has to offer.

Support lifespan
Ubuntu 14.04 LTS will be supported for 5 years for Ubuntu Desktop, Ubuntu Server, Ubuntu Core, Kubuntu, Edubuntu, and Ubuntu Kylin. All other flavours will be supported for 3 years.

Updated Packages
As with every new release, packages--applications and software of all kinds--are being updated at a rapid pace. Many of these packages came from an automatic sync from Debian's unstable branch; others have been explicitly pulled in for Ubuntu 14.04 LTS.

For a list of all packages being accepted for Ubuntu 14.04 LTS, please subscribe to trusty-changes.

Linux kernel 3.13
Ubuntu 14.04 includes the 3.13.0-24.46 Ubuntu Linux kernel which is based on the v3.13.9 upstream stable Linux kernel. Along with the usual collection of new features, fixes and improvements, the following are some of the more noteworthy highlights since the previous LTS release:

Networking - Included Open vSwitch 2.0.1 support (including VXLAN), better bonding support, better bridge management and diagnosis and new buffer bloat avoidance measures. We also introduce better TCP connection management in the face of packet loss, plus TCP fastopen and improved attack tolerance. Intel wifi 6K/7K support was included as well as Infiniband stack updates to provide Mellanox RDMA and VXLAN support. Finally, we see the first stages of the switch to nftables, which should see incremental improvements to network security.
Scheduling - the default I/O scheduler was changed from CFQ to Deadline.

Thermal and Power Management - Power management and efficiency continues to be a focus and we saw the inclusion of the Intel RPL (Running AVerage Power Limit) support for enforcing and monitoring power limits on modern Intel processors. Additionally, we saw the introduction of the Intel PowerClamp driver for improved power efficiency. We also disabled intel_pstate by default as we witnessed poor behavior on some systems (1188647)
Virtualization - As well as major improvements to Xen and KVM (including ARM support for both), we also see VMware support, full support for KVM 2.0.0 (including QEMU KVM), version 1.2.2 of libvirt and the Microsoft Hyper-V hypervisor. Alongside general performance improvements in the virtio subsystems, support for namespaces in containers was also introduced and we finally saw support for unprivileged containers.
Filesystems - general performance and latency improvements have been made across the board for filesystems such as Btrfs, XFS, and Ext4. Metadata checksumming and improved quota support for Btrfs, XFS, and Ext4 have been included as well as Ext2/3 support via the Ext4 driver.

Security - Improvements to AppArmor allow more fine-grained control over applications. See detailed AppArmor release notes below. The Integrity Measurement Architecture has also been enabled. Packaging updates for signed kernels were also performed as well as EFI boot support.
Hardware support - ARM multiplatform support has been added, enabling you to build a single ARM kernel image that can boot across multiple hardware platforms. Additionally, the ARM64 and Power architectures are now fully supported. X32 ABI support (64-bit mode with 32-bit pointers) was also introduced. We also saw copious amounts of HW enablement such as support for Intel Haswell processors, Lynx Point chipsets, Avoton SoC support, i915 driver support for Broadwell graphics, AMD Kabini and Kaveri APU enablement, AMD Sea Islands GPU enablement, and ARM64 APM X-Gene platform support. Also, Ubuntu kernel flavors and architectures were cleaned up with the removal of the i386 generic-pae flavor and eliminating armel architecture support.

Python 3.4
We eventually intend to ship only Python 3 with the Ubuntu desktop image, not Python 2. The Ubuntu 14.04 LTS image continues this process, although we will not be able to convert everything to Python 3 for the Ubuntu 14.04 LTS release.

If you have your own programs based on Python 2, fear not! Python 2 will continue to be available (as the python package) for the foreseeable future. However, to best support future versions of Ubuntu you should consider porting your code to Python 3. Python/3 has some advice and resources on this.

AppArmor
AppArmor has a number of new features in Ubuntu 14.04 LTS LTS. Notably:

Support for fine-grained mediation of signal(7)
Support for fine-grained mediation of ptrace(2)
Improved DBus mediation
New abstractions for applications running under Unity
Several new tunables supporting XDG user directories, dovecot and more
Various policy updates in support of new features and bug fixes

A new @{profile_name} variable to reference the current profile name within policy

New Python and Python3 AppArmor libraries (python-apparmor and python3-apparmor)

AppArmor policy has been adjusted for packages that ship it to work with these changes, but local policy may need to be adjusted, especially for signal and ptrace rules. See man 5 apparmor.d for details.

Oxide
Oxide is a webview based on Chromium to deliver web content. Oxide allows us to better support 3rd party developers and applications within the Ubuntu archive by providing a fast, secure and up to date webengine library for the duration of the LTS. While other web content libraries such as those based on webkit are available, their maintenance will be limited to new upstream minor version releases only, and application developers are encouraged to use Oxide instead.

Upstart 1.12.1
Upstart has been upgraded to version 1.12.1. More details are available in the Upstart Technical Overview.

Unity
Unity Desktop has been streamlined for the 14.04 LTS release. Important new features include:

Support for High-DPI screens and desktop scaling
New screen saver and lock screen that matches the Unity greeter visual designs, with improved speed and security.
The option (under Appearance settings) to show menus embedded in the window's title bar instead of the top menu bar
The application spread (Super + W) has been redesigned, with new features including the ability to type in order to filter the displayed applications / windows
New window decorations, with improved appearance and performance. Windows contents are now updated live as they are resized
Dash scopes can now be enabled and disabled from Application lens, inside dash itself

General
The rest of the Ubuntu desktop also received many updates. Some important changes include:

Nautilus now defaults to type-ahead find instead of intiating a search when you are looking for files within a directory
Many default applications regained well-integrated menu bars under Unity
New Ubuntu-specific settings application, derived from GNOME's control center

Libreoffice
The Libreoffice office suite has been updated to the latest and greatest verision, 4.2.3, containing new features:

General

A new start center gives previews and easy access to recently used documents

A new flat icon theme: sifr, installable with apt-get install libreoffice-style-sifr

initial HiDPI support
Improved import and export filters
support for BCP 47 language tags
support for native MATE and XFCE file dialogs
Writer
a new default document template
in-place editing of text fields
document search for left-to-right languages
spellcheck and change tracking consolidated
Calc
trendline enhancements: multiple trendlines, force intercept, extrapolation, polynominals, moving averages
a new calculation engine, paving the way for high performance calculation on graphics cards with OpenCL
quick right-click context menu to switch between sheets
random number generation and statistic functions
functions to access web data (WEBSERVICE, FILTERXML)
new functions: LEFTB, LENB, MIDB, RIGHTB, COVARIANCE.P, COVARIANCE.S, STDEV.P, STDEV.S, VAR.P, VAR.S, BETA.DIST, BETA.INV, BINOM.DIST, BINOM.INV, CONFIDENCE.NORM, CONFIDENCE.T, F.DIST, F.DIST.RT, F.INV, F.INV.RT, F.TEST, EXPON.DIST, HYPGEOM.DIST, POISSON.DIST, WEIBULL.DIST, CHISQ.DIST, CHISQ.DIST.RT, CHISQ.INV, CHISQ.INV.RT,CHISQ.TEST, CRITBINOM
Experimental features
document management integration: extended to support gdrive

The full list of new features in LibreOffice 4.2 can be found here.

Xorg
The Xorg display server and drivers have been updated to the 15.0.1 release and mesa has been updated to 10.1.

  Ubuntu 14.04 LTS released