So take this one with a huge grain of salt, as it's one of those he said/she said kind of things.  According to a post on CoG there was a link on a Norwegian board to a Gamespot article detailing a bunch of features for the upcoming Mass Effect sequel.  The link has since been pulled, but the information is still available.  Amongst all the nugget of goodness that will be in ME2 is a new expanded squad (up to 5) and the ability to bring human players into that squad for full 5 player co-op.

Some other rumored features of interest include the ability to import your Mass Effect 1 character, a raised level cap of 120, and weapon customization.  According to the post the game is set to have a 6 month timed exclusivity deal with Microsoft for the Xbox 360, because even though Microsoft Game Studio published the first title, Electronic Arts now owns the rights.

Again, right now this is firmly filed under the RUMOR category, but it's one that we truly hope is true. 

Mass Effect with co-op would be SO awesome. 5 player? I don't know if Bioware can do that with their history of bugs. If it meant it was a bit more stable, I would be more than happy with 2 player co-op.

Yeah, I have BIG doubts about this. How can you or ANY of your co-op buddies "Role-play" like that?

Although, the level cap should be expected because of the import which has already been stated from before ME was released. However, it may not be true. They may just import the decisions, but you restart at level 0.

I hope for the former.

Mass Effect was the kind of game that was just crying out for co-op, you already had multiple squad members all you would need to do is make one (or more) of those controlled by another player instead of the AI.

Here's to hoping this rumor is true and that if co-op does come, that it's split screen co-op and not just online co-op.

I could understand 3 player total (you and two friends) because that's the size of the party. Though, there were alot of issues in the first game. I'd hope they fix it all first, then focus on a major feature like this.

Mass Effect with co-op would be SO awesome. 5 player? I don't know if Bioware can do that with their history of bugs. If it meant it was a bit more stable, I would be more than happy with 2 player co-op.

Yeah, I have BIG doubts about this. How can you or ANY of your co-op buddies "Role-play" like that?

Although, the level cap should be expected because of the import which has already been stated from before ME was released. However, it may not be true. They may just import the decisions, but you restart at level 0.

I hope for the former.