IGN reports that the Mercenaries mode of Resident Evil 5 has been patched to support online co-op.
Co-operative play in the game's score-attack mode was said to be offline only when it was revealed last week, but that's already changed via a pre-release title update on Xbox 360. System Link is also supported.
There's no word on a similar update for the PS3 version yet. Resident Evil 5 is out on Friday - read our review for the lowdown.