Canon has been on a bit of a roll with firmware releases over the last few months. Since August, they’ve released update for the 1D X, the 40mm f/2.8 lens, and the 7D. Now, Canon 5D Mark III shooters are up, but they won’t be seeing the update until April.
The planned firmware update will add two major tweaks: uncompressed HDMI pass-through for video, and cross-type focusing up to f/8. This is the same AF tweak that Canon recently released for the 1D X. Here’s the official description of the changes: