So, I decided to not lurk moar, so here's my contribution.
Some minor plot details have been revealed by means of a new set of iGoogle themes based on Gaming. Google seems to be partnered with IGN, so there may be more to this story.
"The second chapter in the Mass Effect trilogy takes you to the darkest reaches of space, where you must uncover the mystery behind the disappearance of humans across many worlds. Travel the galaxy to assemble a team of soldiers and combat specialists, and launch an all-out assault on the heart of enemy territory." ~Description of iGoogle Mass Effect 2 theme.