SPOILER ALERT: Those who want to remain completely pure with regards to all things Mass Effect 3 should turn back now. I'm not going to share any plot spoilers here, or even the full list of newly released Xbox 360 Achievements (via Xbox360Achievements.org), but we're about to start talking about things that you might prefer to avoid hearing. You have been warned.
So as you read above, the full list of Xbox 360 Achievements for Mass Effect 3 is now available on hte Internet for your reading pleasure. The story-based ones range from the no-brainer (Driven awards you 5GS for Shepard's "Return to active duty.") to the alarmingly specific. From the look of things, you'll earn around 330GS just for playing through the story.
There are, of course, other Cheevos that you'll likely pick up along the way as well. Familiar stuff, like the 10GS Shopaholic Achievement, awarded when you "visit a store in the single-player campaign." All of the expected ones are back as well; you can expect to pick up Cheevos for romancing a character, playing through the story twice (or once with an ME2-imported character) and killing an ever-increasing number of enemies.
Interestingly, while there are Achievements for the game's online co-op mode Galaxy at War, each one comes with a solo play-focused variant. Here's an example: the 5GS Tourist is awarded when you "complete one multiplayer match or two N7 missions." They're all like that, as you'll see if you check out the list for yourself. Less surprisingly, there are also no Achievements related to the game's much-talked-about Kinect support.
There's nothing on the list that will ruin the story portion of the game, but take care when reading it if you want to remain completely unspoiled.