The new format is based on H.264 and AAC audio and has a resolution of 960×540, which is exactly half the height and width of 1080p. Sanyo has already announced two camcorders that shoot in this format by default.
The idea behind the new format is to speed up importing and editing by keeping the video in its originally recorded format throughout the entire process.
It’s interesting that Apple would put this in a .0.x update, especially with all of the press that it has been receiving. I don’t really see this as being a big deal, iMovie has been importing HD video as 960×540 for quite a while now. The only change is that now camcorders will begin recording in that format natively.