There are important database changes. You must run update.php after upgrading to this release.
As warned in the previous release, the RDF Schema submodule has now been removed (its functionality having been folded into the RDF module itself). Make sure you've disabled/uninstalled that module before upgrading to this release.
There have been several bug fixes and feed reader compatibility improvements to the RDF/XML and RSS 1.0 output.
A bothersome bug that caused accumulated duplication of RDF data has been fixed. The bug was introduced in the previous release and affected e.g. some users of the File Framework and Calais modules.
You can now use autocompleted CURIEs (compact URIs) on the Administer » Content management » RDF data » Add statement screen, simplifying data entry.
Some minor performance optimizations have been implemented. There will be yet more performance-related work done for the next release.