This video from Imaging Resource shows off some of the new features on the Rebel T4i. The smooth video autofocus you see at the end of the video comes courtesy of the new STM lenses. Right now, there are only 2 STM lenses available – the EF 40mm f/2.8 STM and the EF-S 18-135mm f/3.5-5.6 IS STM, both of which were announced alongside the T4i.
Canon Rebel T4i Hands-On Video
[youtube http://www.youtube.com/watch?v=NRS1RhXpAmM&w=640&h=360]