Twitting your bathroom breaks is frivolous. Like the user who used reddit to report on last year's coup in Thailand, the kids on the streets of Caracas who are protesting Hugo Chavez have a real use for it. They are using Twitter, SMS, camera phones, etc to coordinate, keep people safe, and get the word out as things happen on the scene.

Periodismo De Paz (Spanish)

Update: Sis reminded me about the Usenet posts from "kremvax" during the Russian coup in 1991.