The heavy is getting boxing gloves!

http://steamgames.com/tf2/heavy/kgb.htm

Also, if you look at the page source and the names they've given the icons for the achievements, you can see what they are, and it appears that:

1. The heavy will be getting a sandwich for healing himself.
2. His POW! taunt will kill players just as the Pyro's hadouken does.