Ubuntu 12.10 Alpha 2 is out with an updated kernel (kernel 3.5), filesystem updates (including updates to btrfs), GNOME 3.5 updates, and more.
We'll be seeing Python 3 as the default Python on Ubuntu 12.10 so migration is ongoing. Also, Firefox and Thunderbird are updated to current beta channel releases so that's another way to test out cutting edge software.
More details can be gleaned from the technical overview. As always, practice extreme caution when trying out a development release of Ubuntu.