I have one. It is @Muddy9494 (twitter.com/muddy9494)
I think its useful since I am a game journalist and semi-webdesigner. Would recommend it to some people. I think that more people should use it though.
Have yet to even attempt to use it. I have heard it's basic use, sending one message to many people on many devices at once.
I have yet to really need such a thing.
I have my Myspace, Facebook, and website. I think I'm good for now.