You've probably already seen the leaked weapon and vehicle details unearthed from the Halo 3 beta by modders, but now the no-good dirty hackers have gone and uncovered something even bigger...
By digging through the source data of the multiplayer beta, the modding community has been able to unlock a massive list of on-screen text for both Halo 3's multiplayer and single-player campaign.
One fragment of text modders unearthed was this bombshell:
"The game cannot start because all players are set to observer. Too many players for splitscreen. Only 2 players may play splitscreen coop on the same Xbox 360 console. The party size is too large to start the game. Up to 4 players may play coop on Xbox Live or System Link. Loading information from Xbox Live..."
So if this doesn't turn out to be another Bungie red herring, it looks like Halo 3 is going to sport 4-player campaign co-op via Xbox Live and System Link - a feature that's been begged for inclusion since Halo 1.
Potentially - requiring Halo 3's single-player campaign isn't as rubbish as Halo 2 - this feature could be huge on Xbox Live - and indeed we'll be as happy a butcher's dog if it does in fact make it in.
When Microsoft get back to work tomorrow morning we'll see what it has to say on the matter, but don't count on it being anything other than "we don't comment on rumours and..." etc.