i've been asked several times over the last year about "what's twitter?" and "why should I use twitter?" while i'll be the first to admit that you don't really "get" twitter until you actually start using it, and you get equal value from twitter as you put into it.
so i've compiled a list of links to resources giving the various ways people are using twitter, as well as a post i wrote a while ago when i first started using the service. since then it has EXPLODED into mainstream use.
without further ado:
here's a couple links to help you learn more about twitter and whether it's for you or not:
probably more info than you ever wanted to know about Twitter, but this should give you a good idea about what it is, and how people use it.