Linux Journal published an article on the new features of VirtualBox 4.1
We first covered the release of VirtualBox 4.0 back in January. Amongst other improvements and new features, 4.1 adds VM cloning and a nascent PCI passthrough feature.VirtualBox 4.1 Introduces Cloning Amongst Other Features
The new cloning feature allows the user to easily make a copy of an existing VM including the hard disk image and all associated settings. It’s going to be particularly handy for people like me who create a lot of blank VMs with similar specs. This means that I can create a generic Linux 2.6 supporting VM with 1GM of RAM and a virtual HD of 8GB and then simply clone it when I need a new one. The speed of the cloning procedure varies according to the size of the HD file. For example, cloning a fresh VM with an unused dynamically scaling hard disk image takes almost no time, whereas cloning my Windows XP VM with a 4GB partition took a few minutes.