Ubuntu 11.10 is out with a revamped Software Center, improved Unity (with Unity 2D as fallback), successful migration to Gnome 3.2, Thunderbird as the default email client, LightDM and many more.
Software Center gets UI re-design to make discovering new apps easier.
Unity 2D is now available as a fallback option for those that don't have the required hardware or drivers to support Unity.
The Ubuntu Font gets expanded and looks superb in terminal. Of course, it also looks superb as the default system font.
Ubuntu finally gets a backup tool in the default installation. Deja Dup gets to fill that role.
LightDM is the new login manager but seeing as how so many people (myself included) uses auto-login it doesn't seem to matter much beyond improving boot times.
With Gnome 3.2 as the new base, there's a lot of changes all over the place. Nautilus now looks and behaves a little differently, for example. You'll need to experience it to know it. I'm sure a lot of users are going to grumble about the rather spartan settings available.
We get kernel 3.0 for Ubuntu 11.10 but the recent power management bugs will not be helping mobile users maximise their battery life, unfortunately.
Check out the release notes for more info on the Ubuntu 11.10 release.