Although I don't have much interest in Eberron - I've only played it a couple of times, and I wasn't overly impressed (no offense to any of ya'll who *do* like it ... just my personal impression) - I would say that a FAQ would be the way to go.
Mass "lecture" periods about Eberron - be it MSN, chat, or message boards - would be great for instant gratification for the immediately surrounding audience, but people who dribble in later wouldn't have resource to that plethora of knowledge that is derived from picking a knowledgeable person's brain.
Unless, of course, there was a Magi and/or a non-Magi contact(s) for people to direct questions towards; that might help, too.
The problem with a FAQ, of course, is that you're trying to describe a whole new setting, and have to pick which parts to include and which parts not to, lest it get altogether too wordy. You also have to find someone who can make be relatively concise, as people's attentions seem to wander, and too much information too soon can cause potential readers to become disinterested. And of course, there's the time/"who can or who will do it" issue.
If you can persuade some sorry fool to do it, though, it can work out pretty good, as long as said fool can get it done punctually. Just ask me ... I've been working on an FR FAQ forever and a day now.
Of course, that's all a lot of work to be doing for a possibly, maybe, might-be-might-not tentative setting, which is dependent on an interested Magi accepting the burden of Eberron setting coordinator - and Gabe's desire to do the programming necessary to create the room, et al. So maybe a mass Q&A session/"lecture" period would be more suitable, at least for right now
... oops, did I say 'fool' out loud there about the FAQs?
What I meant was er ... heh ... *sneaks away*
