Ubuntu 12.10 Beta 1 came out with a new X.Org stack, updated Unity, OpenGL ES support, Linux kernel 3.5.3 and more.
Update Manager is now called Software Updater. Meanwhile, the migration to Python 3 proceeds with most Python apps included in the desktop now using Python 3.
There's now just a single unified 800MB disc image for the Ubuntu desktop. The 700MB desktop CD image, alternate image, and DVD image are no more.
You can get more details from the Technical Overview.