Reports are that Mass Effect 3 will indeed have some form of multiplayer. The first details of which are apparently the scoop of PC Power Play, an Australian magazine.
“That’s right – Mass Effect 3 is getting multiplayer!” teases Daniel Hindes. “We travel to BioWare’s office in Edmonton for hands-on time with the series’ first foray into online gameplay, and chat with Mass Effect Series Producer and Mass Effect 3 Project Director Casey Hudson about the decision to go multiplayer in the epic battle for the galaxy.”
Source: computerandvideogames.com