Sakai was updated on Thursday, August 21, from Sakai 2.9 to Sakai 10 (technically it's Sakai "2 point 10" but numerically that is the same as 2.1, so they just call it 10).
There are lots of bug fixes and a few new features. OIRT has an overview of the improvements on the Sakai New Features page, or you can look at the full list of new features at the Aprero Sakai 10 Release Notes page.
