A brand that gets Twitter

Darryl Ohrt, from Brandflakes For Breakfast, tells how he noticed a tweet from Jet Blue warning NY travelers about impending whether delays. This prospect is so simple and so obvious, one would think other companies would already be doing this.
All it took was for this brand to figure out how this existing tool could be of service to its consumers. Through this simple gesture Jet Blue shows that the brand gets them, knows what they need and from a branding perspective gets how to be a part of their day in a relevant way.
One industry that could I could think of that could sorely use this tool to build their brand, are doctors. Rather than the typical waiting time of up to an hour in the waiting room, how great and easy would it be for a doctor's office to twitter their patients that the doctor is running late? Nix the cards on my birthday, a doctor could show me they care by showing me they respect my time.