In part 2 of our Video ISO Comparison of the Rebel T2i and the EOS 7D we take the two camera's through the range of important high ISO's in a brighter room. This should help you compare noise levels, which weren't so easy to do in the darkened room.
After viewing this comparison I have to say that their ISO levels are virtually identical. It's possible the 7D has an edge at some of the ISO settings, but if it does it's not always easy to identify.
Two notes about this video:
1) The graphic at the beginning shows a Rebel T1i in error. I pulled an image and didn't look close to make sure it was the T2i.
2) In the last comparison of the video, where both camera's are set at ISO 100, the Rebel T2i was not correctly split in editing, thus you cannot compare ISO 100 in the dark - something that seems a bit silly anyway.