I just saw this pop up in my account - Facebook will let us use SMS as an alert-based service. Interesting.
From what I've gathered right now, you can get alerts for wall posts, pokes, comments, inbox messages and a few other things. Oh, and if you want, you can subscribe to someone's status feed by typing in their name either via SMS or the web interface.
The service works with Warid, Mobilink and Telenor in Pakistan. I'm sure they have support for other operators abroad.
And this comes amid my decreased usage of Facebook. Interesting, indeed.