Housemarque has announced that Dead Nation will going to feature an Online Co-op.
Llarl Kulttein said on EU PS blog that intially there wasn't any planned to bring this online co-op to Dead Nation, but after having some discussion with Sony they decided to incorporate it in the game.
“Originally, online co-op wasn’t going to be included as a launch feature as the schedule and resources didn’t allow it,”
“However, after many late night testing sessions and long talks with Sony, we decided that this was a must-have feature and it would be unfair on you if we launched without it.”
Dead Nation will be launching on Playstation Network later this year.