I agree no one will pay for friends. You can get them easily enough without paying, just by interacting with people and searching for users that Twit about relevant stuff.

As much as people here think advertising is boring, I think Twitter could actually have a great contextual ad business. As long as the ads are relevant. If someone Twitters about HD TVs, would they not be especially be engaged by an ad for TV's? What about people who tweet about flights seeing ads from airlines? There is a lot of potential there.