Execution: Make it known in the Blogosphere that there is going to be an event. Use wiki and othere tools to do all the formalities. Organize volenteers. Make it as unstructured as possible. Add fun, geekiness. Add sugar , spice and all good things like power puff girls :) . Get goodies like geektoys and iPods as give away to attendees. Get sponsor(s) to underwirte the minimal expenses.
Profit: A forum to seed viral marketing is alive and kicking.
Repeat the event with improvement at every step of the way, it is a runnaway success.
Case in point:
Pinko Marketing evangalized by Tara Hunt
Many such ideas based on the clutrain momentum are emerging! Watch out and surf on them!