Twitter can actually be helpful if used properly. Unfortunately, too many people use it for brainless self-promotion ("I'm going to bed now. Goodnight.") and "tweets" that don't add any value to your life.
I believe in using these technologies for information and teaching. I use this blog for that purpose (and of course, it's used to sell DVDs and promote the online school as well) but without decent information that helps people, there would be no reason for anyone to visit this blog.
Twitter is the same, and should be treated as more than just a way to send inane announcements and random thoughts to friends.
If you use Twitter, I urge you to go to http://twitter.com/sifugullette and sign up as a follower to get information, quick links to interesting stories, and tips that might help in your practice, study, and knowledge of the internal arts of kung-fu.