Do You Use Twitter?

Even after reading so much about Twitter, I am still unsure about what it can be useful for. Looks like a mixture between blogging, instant messaging, IRC-style discussion groups, everything together cooked up in a pot and carefully stirred. The AcademHacK blog gives a few firsts shots about one can use Twitter professionally, but what do you think? BTW: I have opened my own account, but still experimenting.