It looks like achievement pages have opened up for Halo: Reach, Joy Ride, Shadow Complex, Forza 3 and Alan Wake over at xbox.com Although the pages all are blank at the moment they are a pretty good indication of what MS has up its sleeve to announce in the next hour or so. Credit Destructoid for the tip.
Thanks btw to the bombers out there quickly building game pages for these titles as they get announced. It helps a lot over at headquarters.