The New York Times today has an excellent story on social communications and how it is rapidly becoming the 2.0 generations idea of texting.
Using services like Twitter, Jaiku and a few others these days have made SMS almost passe for me. But, using them responsibly is the key. Yesterday someone asked me what's the polite way to take someone off your Twitter list, because the person had become a nuisance. My advise was to tell them why.
I've used Twitter a lot in the last few weeks, but as rapid messaging system to get information to people and as a fast way to set what I call "casual status."
For example, when I was on the train yesterday coming back from a weekend trip to Santa Barbara I let folks know where I was and what I was doing. Even though I was online almost the entire trip up and back via my EvDO card from Sprint there was this calming effect of not being slammed by IM's and emails that Twitter provided. Of course the tweets from Twitterific do cause some to take notice, but all in all, it was like IM meets SMS for me, and that was a good thing.