"Multiplayer Programmers ensure the game engine and game systems work reliably and efficiently in a multiplayer environment. They work with both the front and back ends to take existing single player user experiences and make them multiplayer safe."
nope I don't know if I'd rather have co-op or competitive multiplayer. I would potentially want them both. Mass Effect 2's combat was much improved over its predecessor and could lead to a fun multiplayer experience.
On the co-op side, the game is setup for 3-player play if it's just going to be added to the existing game framework. There's always a chance that this is the beginning of an MMORPG, but I don't believe BioWare would throw two of those into production at the same time. I think we'll have to wait until after Star Wars: The Old Republic is released before we have a chance at getting a Mass Effect MMO.
The job responsibilities also mention working on multiple platforms, seemingly confirming whatever this is for the Xbox 360 and PC versions. The job posting is very close to E3 2010, which could shed some light on this when it kicks off on June 15.