Cinnamon is a desktop environment built by the Linux Mint team and it's implemented by default in the Mint OSes. The current update, 2.4.7 is just a maintenance one, but it's pretty extensive and it comes with a ton of changes.
Numerous updates have been released in the 2.4.x branch of Cinnamon, and it looks like the developers are not done with it, not by a long shot. They have already detailed 2.6.x, but it looks like that version is still pretty far away. In the meantime... (read more)