As you probably know, Google launched the Buzz project quite recently. This is something in between blogs and twitter - you post messages that appear in a followers' roll, and those are not restricted to 140 symbols. You can also link Buzz to your blog stream or posts you share in Google Reader - they will appear there immediately.
A few scientists already took advantage of this, for instance here is the Buzz stream of the Field's medalist Terence Tao. For Russian speakers I would recommend the Igor Ivanov one.
If you use Buzz or know anyone from the scientific community who does, drop a comment about it. )