Check out a few pics from this week's San Diego Comic Con of what I believe is the Captain America costume for The Avengers.
Update: This is, indeed, for The Avengers. Marvel released another pic (last one) stating this to be from Cap's "Ready Room."
Click to enlarge.
Image Sources: ComingSoon.net
For more from the SDCC head on over to the Cosmic Book News 2011 SDCC News Hub.