This is along the lines of what I was imagining, too.
I plan on contacting all the users from the DC preDevCamp list who are on Twitter in the next day or so (most of them are on Twitter) but have not done so yet.
Alice, how many folks do you think might meet up from Balto area for a conjoined DC/Baltimore shindig? After I've talked to all the Twitterheads I'll get a number for DC and we can have better expectations for space needed, etc.