Q. Do celebrities actually communicate with fans on Twitter?
A. The answer is a big "it depends". Some celebs like Ashton Kutcher have well over a million followers and it could be extremely difficult to have traditional Twitter conversations with others. But this does not mean they do not read the Tweets directed to them (@mention), and appreciate kind words and "fan mail".
Some celebs use their account more as a broadcast tool to build their brand and announce what they are doing, rarely reading tweets directed to them or about them.
Some celebs, while they have a presence on Twitter, have their manager or other hired help run their account for them.
Advice for communicating with celebs: go ahead and send a tweet to your favorite celebs by beginning the tweet with their Twitter id (@nickname) and DO NOT expect a response, and you will be plesantly surprised if you do.
Tip: You can actually look at a celebs profile and look for Tweets starting with other users Twitter ids to see how active the celeb is at responding. Keep in mind that these responses may be other celebs, but you can easily figure that out by checking out profiles.