It’s almost a given for new Canon DSLRs to have an HD video recording mode, but older Canons can also capture HD video with the open source software EOS Camera Movie Record. The program allows you to shoot HD 720p video with any Canon EOS camera that has LiveView capabilities. The software runs off of your computer and captures HD video from the LiveView of a tethered camera.
Obviously, the fact that your camera has to remain tethered limits use of this video feature largely to studio use, but it’s a neat workaround for Canon owners. Unfortunately, despite the fact that the Canon program has been in the works for over a year, there’s still no Nikon equivalent.