http://support.microsoft.com/kb/2460045
Key areas of improvement:
- Improve support of IE9
- Recycle Bin could now be restored from Site Colleciton or Web that has been deleted.
- RBS and shallow copy features to improve efficiency by moving pointers to database instead of moving databases.
- Folders storage details on SharePoint site.
- Support for MS SQL 2011.
- More Robust search host distribution service that improves error recovery and performance during search crawl.
SharePoint update details could be found at.
http://technet.microsoft.com/en-us/sharepoint/ff800847.aspx
