Here are the release notes from Sitefinity.com forum :
"We are happy to inform you that Sitefinity 3.0 SP2 is already available for download from your Client.net account. Note that this time we are also providing a zip containing the files necessary to upgrade projects created with previous versions, without the need to uninstall Sitefinity 3.0 or SP1. Replace the files in the C:\Program Files\telerik\Sitefinity3.0\ProjectManager\EmptyProject to make sure new projects are created with SP2. Also Community and Standard editions can be installed on single machine.
Major fixes since SP1:
Problems with database upgrade scripts
Problems with treeview in Templates
Head tags in Templates
Page group operations
Issue with module create permission (blogs, polls, lists)
Issue with default menu behavior for styling selected items
Issues with comments filtering and search
Issue with locking a page by multiple users
Issue with immediate publication on creation of a new page
Issue with multilingual for Generic Content not displaying on public pages
Yours truly,
the Telerik team"