A few highlights of the new version:

* Moved to git source code management to make community participation easier.
* Easy PDF export and export to other document types through OpenOffice
* Code removal and re-factoring to strengthen the platform foundation.

You can review the changes made and bugs fixed since 3.0 by going to:
http://www.xwiki.org/xwiki/bin/view/ReleaseNotes/ReleaseNotesXWikiEnterprise31M1

And download the new version:
http://www.xwiki.org/xwiki/bin/view/Main/Download