So Twitter is going to look to deploy commercial for-pay tools by the end of the year:

“We’re looking at who’s using Twitter and for what,” Stone told the Reuters Global Technology Summit in New York via videolink from San Francisco. “Are there any commercial usages that are making a lot of sense?”

That's Biz Stone, Twitter founder (neat name?). I can imagine the Twitter's base will whine and moan for a while, then grow as they bring more services online.