Ok, Let's be clear; I don't really feel comfortable posting to twitter. If I'm talking to a friend, I'd use a more private method of communication, If I'm talking to a stranger I don't like the idea of just dumping a question or comment on someone's lap without some sort of introduction. It's like sticking your head into a celebrity's window and shouting "WHEN IS YOUR NEXT MOVIE COMING OUT?".
It does work pretty good for gathering information; people post links, quotes, thoughts, whatever. If they have similar interests as you and post regularly you've got a pretty good personal assistant finding you the best of the internet.
It's hard finding the good people to follow in bioinformatics, there are two types of people: Ones who are bioinformaticians who tweet and ones who tweet about bioinformatics. There is a difference, the former will post things like, "Writing grants, oh noes" (which is not useful) and the later will post "Paper about next-gen sequencing [link]" (which is useful). Here's a list of the ones I follow that are worth following:
Web 2.0 and science:@NextGenScience
Personalities and celebrities are a bit easier to fathom, here's my list: @happy_khan/personalities