Following up on my earlier post on microblogging, I saw a thread on the TechRhet listserv regarding this subject: essentially how might one use Twitter in the writing classroom?
The general consensus in the thread was that there was a potential to teach concision in the 140 character limitation of the tweet. There was also extensive comparison to the haiku. Well, a tweet may sound like its a haiku on the classic subject matter of nature or spring, but that's about as far as it goes.
Writing a short message is not the same as writing a concise message or a haiku (btw, I would not characterize haikus as concise; there's a different aesthetic @ work there).
Fortunately our students don't need to be taught how to write short messages. They probably write more than their instructors. Obviously the 140 character limit reflects the important connection between microblogging and SMS. And as we know the point of texting is not to be concise! In fact, the opposite is closer to the truth. In microblogging we say anything and everything b/c it's quick, easy, and free.
A couple other observations...
1. As many others have been pointing out, there are a lot of different microblogging formats and each has particular uses. Twitter seems to be for sharing information. Pownce lets you share media and create events. Plurk might be better for conversations (or so folks are saying). Seesmic gives you video microblogging. Brightkite adds a locative element. Jaiku lets you add various feeds and other customizations (haven't had a chance to get in there yet... anyone got an invite?). And so on.
The point is that there isn't just one microblogging genre.
2. Microblogs facilitate collaborative, real-time, multimedia compositions. So that's not about being concise at all, right? It's about me and my colleagues on our mobile phones covering an event and sharing media from different perspective, honing in on an emerging composition.
3. Then there's the texting novel factor: the serial microblog.
In any case, there are many interesting things to explore in the compositional practices of microblogging, not the least of which is the ongoing meta conversations in these beta communities. Here is an (another) opportunity for students to explore how technological contexts shape rhetorical, genre, ethos, etc. Being concise could be part of it, I guess, but it hasn't been, at least not that I can see.