An upcoming issue of Xbox World 360 Magazine claims to carry some information on a rumored multiplayer mode in Mass Effect 3, according to the cover which was posted on NeoGAF. It was said the new mode would supposedly debut at gamescom, and would be playable at UK trade shows in September. Now it looks as though this is just indeed a rumor, despite the mag cover not specifying it as such.
Turns out, another GAF poster with the magazine in hand straightened it all out a bit more by quoting the paragraph dedicated to the feature line on the cover:
"Well, if you believe the rumours - which we certainly do - Mass Effect 3 will have multiplayer. According to various sources, there will be a batch of 3 player co-op missions that run parallel to the main story, with each player assuming the role of a single squad mate. It seems likely that this will happen, and it'll form part of EA's Online Pass system. However developers have been known to ditch multiplayer during development in the past, if it doesn't work..."
So, basically, it was nothing not reported before already but instead of calling it co-op, it was labeled as multiplayer.
All's right in the world again then, we reckon. Hopefully more on this rumored co-op bit, or whatever Secret Feature X is - if they are the same thing - will be revealed soon.
Thanks, Gematsu. Thanks for the update, Moonwalker1982.