The LittleBigPlanet Community has so far 8 heroes and 2 villains as costumes for Sackboy. At Comic-Con, Marvel gave details on which characters would appear in the third pack and Pete Haas from cinemablend.com has the full description.
"At Marvel Interactive's panel discussion, details on the third Marvel costume pack for LittleBigPlanet were announced. The DLC pack will add five new costumes for your SackBoy/SackGirl.
Upon downloading Marvel Costume Pack 3, you'll be able to dress your character as Captain America, Wolverine, Venom, Invisible Woman, and Rogue. The pictures haven't hit the Internet yet but rest assured they've got the same cutesy aesthetic as other LBP creations. For example, the "A" on Captain America's helmet is held in place with tape.
The release date of the pack wasn't announced. The second Marvel Pack was released on July 20th. There are four costume bundles planned in total."
I honostly thought those white lines on his head were his eyebrows.
Hopefully the pack won't have a 2 week wait like the second one. If not, images will probably come out later the coming week.
Thanks to Pete Haas for the article