@Carl Hancock - VideoPress outputs videos in an MP4 file container with H.264 High and AAC-LC as well as an Ogg file container with Theora video and Vorbis audio.

Codecs such as H.264 are actually a family of standards grouped into Profiles and Levels. The current iPod touch and iPhone 3GS hardware supports H.264 Basic Profile video. The iPad supports H.264 Main Profile video.