Relic's mildly disappointing orc-eviscerating game Space Marine is getting a 4-player co-op mode later this month, with THQ dating the roll out of the free upgrade for the 25th. It's called EXTERMINATUS. Which, quite coincidentally, is my middle name. There will be two scenarios in this mini-expansion, in which you can play as tactical marines, heavy-weaponised devastators or whoosh-bam marines. You'll be fighting orcs and chaos, according to EG.
Nor will this be the end of DLC for the game, say Relic, with paid and free additions to come.