Fallout Online's official website. According to a press release issued alongside the tease, it seems that this is just the first of many "tales from the wastelands" that early registrants will receive. Additionally, registrants will be "fast-tracked" for participation in the game's private (and eventually open) beta.
Interplay's "coming soon" game page still has "Project V13" (now better known as Fallout Online) listed as a 2012 release, so, ya know, we probably won't be venturing into those wastes anytime soon. Then again, by 2012, we might be wandering in the wasteland for real.