When I first learned about Twitter at SXSW 2007 I was somewhat critical of its utility. (or lack thereof) I'm still not totally convinced it's practical beyond the following uses:

• locating friends at a convention
• letting friends know how bored you are in the class/convention panel you're attending
• making sure total strangers understand exactly how important your friends/social plans/creative projects/Hollywood meetings are
• asking questions about new iPhone apps
• answering questions about new iPhone apps
• exhibiting your deliciously pithy wit
• smashing a bunch of keys with giant thumbs and hitting send (applies only to Shaquille O'Neal)
• telling people you're "friends" with Stephen Fry

Of course, all of that hasn't stopped this hypocrite from adopting Twitter. If you have a very short attention span and wish to follow my Internet twitter litter trail, you can do so at twitter.com/trembledotcom.