Unity 2D dropped from Ubuntu 12.10 "Quantal Quetzal"
The 2D variant of Canonical's Unity desktop user interface – introduced in Ubuntu 11.10 for systems without 3D/OpenGL hardware acceleration – will not be included in future versions of Ubuntu. The change was first discussed at the last Ubuntu Developer Summit (UDS), but has only just been confirmed in a bug report that sees the removal of Unity 2D.
From the upcoming 12.10 "Quantal Quetzal" release onwards, the Linux distribution will only support the 3D version of the Unity desktop. For systems without graphical acceleration, Ubuntu will instead fallback to the Mesa 3D LLVMpipe driver, which performs 3D calculations using the main processor. Ubuntu isn't the first distribution to use this method for dealing with these types of systems: the Fedora project already uses LLVMpipe in Fedora 17 to run the GNOME Shell when graphics acceleration isn't available.
Ubuntu 12.10 is currently available as a third alpha. According to the Release Schedule, beta versions of 12.10 for testing will be available in September, while the final release is expected to arrive on 18 October.