The notion of physicians using Twitter appears to have entered the zeitgeist, as this Grey's Anatomy clip evidences. In the episode, the staff of Seattle Grace debate the ethics of tweets sent by one of the surgeons from the operating room. As you might expect, the conversation barely touched on patient privacy and instead focused on Twitter's potential as a powerful educational tool for medical students and communication tool for hospitals (which is also possible, given the right circumstances).
Nevertheless, in the real-world, as web-savvy doctors have warned, taking precautions to protect patients' interests when tweeting requires a more thoughtful discussion. Katherine Chretien, MD, a hospitalist at the VA Medical Center in Washington, DC, offered an interesting solution in a story on NPR:
She suggest it's time to think about verifying Twitter accounts for doctors, as some already are for celebrities, politicians and even a few journalists. Besides giving the public more confidence in the tweets, it might also make medical tweeters more accountable.