I've been trying (really I have) to discern true useful applications of Twitter for myself in a academic environment. At it's heart, Twitter is a really easy way to let individuals know what you're doing on a minute-by-minute basis either through the Web, IM or texting. For example: I just scratched my nose. That would be an awesome Twitter entry and well below the 140 character limit per post. One of the 23 Things videos explained that your friend wouldn't have to need to know that you're mowing the lawn, but then went on to say that others might like to follow what you're doing? My immediate reaction is why? Who has the time to post about trivial matters or read about them? To me, Twitter undermines concentration, focus and deep thinking and puts in its place scattered tidbits of gossip. Think of a bird, fluttering its wings and darting here and there. That's what Twitter does a thousand times over.
I do see a use for it as another means of querying a certain group on a question or problem. Instead of inanely posting gibberish it could be used as a means to get answers. Twittering conferences, is fine I suppose, but wouldn't it be better to summarize the speaker and then blog about it?
The reference applications of Twitter deserve further consideration. Right now, our online reference tools don't get that much use, but if our users start using Twitter then we need to be there as well. I've already begun discussions on setting up a library Twitter account for publicity purposes.