This should come later in the F/LOSS and Web 2.0 101 series, but Twitter is a fun and simple tool with huge potential. I've begun using Twitter, and have it updating my Facebook account as well. MIT's Technology Review has a great article on Twitter and where it came from (Use bugmenot.com's database of login username/passwords to free sites to read the article without registering). Twitter is a simple, one-trick site - you update your status and everyone who's "following" you sees that status update pop up - on the web, on Facebook, and even, most importantly, on your cell phone. Naturally, you can also update your Twitter "microblog" from your phone, facebook, or the web - you can even direct an RSS feed from it. At Youth Service America, we send our grants RSS feed into Twitter, so anyone following that feed gets a buzz on their cell phone anytime we post a new grant.
As a Peace Corps volunteer in Jamaica, I created an intranet for our volunteers. It was free for our cell phones to receive SMS text messages, but costly to send them. The intranet organized volunteers by city, sector and Peace Corps group number, and interacted with SMS messaging. Any volunteer could send a text to kingston-cell@our intranet.org and it would redirect to all the volunteers in Kingston, Jamaica. Or, HIV-cell@, or group73@... You get the idea. Volunteers on the intranet could also subscribe to specific news updates lists, weather/hurricane alerts, and were somewhat forcibly subscribed to a security situation update list.
What does this have to do with Twitter? Well, it means I did a lot of work that I didn't really need to do. Had Twitter been around then, we could have simply created a few Twitter accounts for the various important lists and gone from there.
A Mobile Strategy already built for you
What does this mean? Well, in a global world where phones with SMS text messaging are more prominent communications devices than wifi internet access, or simply going to the communications medium that your constituents are using, Twitter is a fast and free way to have a mobile strategy overnight, and even better, to have it automagically integrated with your website's RSS feed, a blog, your facebook page... the integration options are limitless!