Sen. Claire McCaskill sure is famous these days. She's one of Barack's best buds and gets access to uber-VIP events! She's on Meet the Press! Rachel Maddow loves her! I learned all these wonderful facts and more by following my Senator on Twitter. Unfortunately, all the fame seems to be really swelling her head and preventing her from "getting" how Twitter can be useful for enhancing democracy rather than simple navel-gazing.
I'm a relative newcomer to Twitter, as I've only been tweeting for the last two months. But I know that much of the power of Twitter is the ability for regular folks to have back-and-forth conversations with people we've never been able to access before: Karl Rove, Shaquille O'Neal and MC Hammer are three of my personal favorites. Several legislator/Twitterers have put this interactivity to good use, managing to attract and follow thousands of people and engage with them in a real way about the innards of government. Particularly acitve and astute Congressional Tweeters include Sen. Jim DeMint, Rep. John Culberson, Rep. Bob Latta, and for bipartisanship's sake, Rep. Marcia Fudge.
Sen. McCaskill has unfortunately only used Twitter as a one-way communication tool, choosing to follow only one person: her press secretary. Having worked for a U.S. Senator, I certainly don't expect McCaskill to peer over her laptop for hours a day, reading thousands of tweets from random folks around the globe. But it's not unrealistic at all to expect her to interact with SOME of her constituents on Twitter. Her refusal to do so is both a display of arrogance and a missed opportunity to be held accountable by her constituents.