Joomla 3.1 is now available.
3.1 is available as a one-click update for all Joomla 3 users.
The major new feature in 3.1 is Tags. We wrote a detailed introduction and said that Tags "is one of the best new features to be added to Joomla in a long time."
In addition to Tags, there are some bug fixes and 7 security fixes, so we recommend that Joomla 3 users update immeadiately. If you have a lot of sites, try using Admincredible.com to update quickly and easily.
A Video Introduction to Tags