A new version of Unity (3.8.6) has been released today that brings new configuration options for changing launcher behavior and many other fixes for bugs and crashes.



From UbuntuVibes:

Until now, unity launcher was only revealed when the pointer was hovered on top left corner of the screen, over the Ubuntu button. But today's update changes this default behavior and and now Unity launcher is revealed whenever pointer is moved on to the left edge of the screen. To avoid accidental revealing of launcher, it seems that a certain timeout has also been kept.

  Ubuntu 11.04 Changes - New Unity Update Brings Options for Adjusting Launcher Behavior