Depends what potential uses you're referring to. If it's context-sensitive advertising, ICQ did have (has?) ads and supposedly could match an ad to a message text or a user's history.

It's still only traditional advertising, the thing about Twitter is it has the ability to make people forget they are bing advertised at. People follow company account on Twitter very willingly and receive a stream of what would be considered advertising from the company right mixed in with everything else they are doing.

The ICQ equivalent would be to have someone like starbucks open up a chat with users and still manage to somehow retain the users.

Fair point - but, this relies on the user actively using Twitter over some time, which seems like the minority. Couldn't companies achieve the same with Facebook pages, which seem to have a larger and more devoted audience?

Yeah, at the moment though Twitter has more potential in this area. They are seen as more of a broadcast platform whereas on Facebook the pages are tacked on to a platform for more personal communication between friends.

Certainly though I see this growing on Facebook to, I don't think there is only room for one game in town here though, so far companies have been happy to work across both platforms. Depends a lot on Twitters future user retention and engagement I guess.