TwitterLocal, the service (formerly known as TwitterWhere) that allows you to grab an RSS feed of all the Twitter users for a given geographic area---like Portland for example---has just released a "Leader Board" that ranks the top 30 cities by Twitter use.
The service uses a rolling 24-hour snapshot of Twitter use, reordering the leaders accordingly. So who's leading whom right now is likely quite different from what you saw on the TwitterLocal Leader Board the last time you looked.
TwitterLocal is the creation of local map-savant, Matt King, a ridiculously productive developer with a knack for twisting mapping APIs to his creative ends.
