Co-worker walks away from workstation with an internet connection, with the browser logged in?... Could this point to a possible poster?
Alternatively, did someone perhaps scam a password at a Georgetown wi-fi hotspot? It's easy to forget how simple some of that sort of thing could be. If DNC activists could actually arrange to tape a cell phone of a conference call with Newt Gingrich ("on their way to the grocery store, in their car") it shouldn't be to hard for a determined Dem hacker to find a Freeper in Starbucks, and pirate their password.
But the simplest explanation might be - someone didn't log out?
I remember in college the way people who forgot to log out for a momentary break - were mercilessly abused. Mostly quick posts to newsgroups looking for some sort of remarkable encounter of the amorous variety. :)
Could this have been a more subtle / sophisticated of the "I'm looking for a date with a single poodle this weekend" sort of shenanigans with a logged on account, so many will remember (hopefully just seeing, laughing at someone else's misfortune)?...
Just a thought.
Remember to logout. Use a wired connection. Encrypt if you don't.