With Canon's new firmware for the 5DIII, the words that most come to mind are - finally, about time, what took so long, and when can I buy one.
Uncompressed HDMI Output Support
When shooting video, HDMI Output makes possible the recording of high-definition uncompressed video data (YCbCr 4:2:2, 8 bit) from the EOS 5D Mark III to an external recorder via the camera’s HDMI terminal. This, in turn, facilitates the editing of video data with minimal image degradation for greater on-site workflow efficiency during motion picture and video productions. Additionally, video being captured can be displayed on an external monitor, enabling real-time, on-site monitoring of high-definition video during shooting.
The caveat here is that the firmware is due out April 2013. That's ridiculous! This feature should've been on the camera from day 1, as in March 1, 2012. My guess is that this announcement, 6 months pre-mature, is to help stem some bleeding on Canon's part as more manufactures (i.e. Nikon, Sony, Panasonic) are coming to market with cameras that already do this today. Canon doesn't want to lose current customers to other manufactures. And Canon also doesn't want someone to stop considering a future purchase of a Canon product because it's lacking in features compared to other entries on the market. This firmware announcement seems more reactive than proactive. Nevertheless, it's a welcomed improvement. Competition is a good thing.
Update: CanonRumors proposes another good reason why Canon is being pushed (forced?) to offer clean HDMI out:
Maybe the recent clean HDMI out software from Magic Lantern forced their hand.
I'm guessing it's all the above. Sony + Nikon + Panasonic + Magic Lantern = Canon Firmware update