Ubuntu 10.10 Alpha 2 pulls in plenty of updated packages including the latest snapshots of the GNOME 3.0 and KDE 4.5 desktops, the Linux 2.6.35-rc3 kernel, provides the Unity Desktop by default with the Ubuntu Netbook spin, and various other Maverick features continue to be tackled. Since Alpha 1, support for installing to Btrfs has also been added to Ubuntu's alternate CD installer. There's also X.Org Server 1.8 to play with until X.Org Server 1.9 has been integrated last month along with other updated X components.
The Ubuntu 10.10 Alpha 2 release announcement can be found on ubuntu-devel-announce, which provides download links to the various flavors of Ubuntu. There's also this Ubuntu page that provides a few more details on this second alpha release.
A third alpha release for Ubuntu 10.10 is expected in about one month's time (the 5th of August) while the final release of the Maverick Meerkat is expected for release on the 10th of October.