There are 3 teams of people I know of that are working on an mmorpg.
The first one you can see here.
http://www.gpinteractive.com/shadowsgate/
looks promising, and I've heard they've already played a beta multiplayer game test. As for mmorpg? Well, I don't know the exactly how many people were actually able to play at one time, so I don't know if it's "officilly" a mmorpg in dbp.
The second I hardly have any information about, for they hardly talk about it, or are hardly seen at the forums.
The third, I'm not allowed to talk about. All I can say, is that the programming of multiplayer hasn't been started on yet.
MMORPG possible?, well, if you're talking 1000s of players then no. 100s of players, no. Either 100, or 64 is probebly the max I see DBP going, which isn't too bad.
A book? I hate book. Book is stupid.