First a few background facts for you:
1) Andy Roddick and Serena Williams are big Twitter users.
2) People bet on tennis.
3) There have been some stories about players allegedly being involved in throwing matches or otherwise being involved in betting shenanigans. The highest profile case involved Nikolay Davydenko. He was ultimately cleared of throwing a match in 2007. (Interesting story. This was a first round match. Davydenko was ranked 4th; his opponent was ranked 87th. Davydenko won the first set 6-2. THEN, a big chunk of $7 million was bet against him winning. He lost the second set and then retired with a foot injury in the third set. BetFair voided all wagers. The ATP launched an investigation, but cleared him of wrongdoing.) In July, another player, Mathieu Montcourt, was found dead after he was banned from tennis for betting on matches. He was found dead in a stairwell. The cause of death has not been determined. Make up your own story. There are lots of other stories about betting problems in tennis. I was going to catalog them, but it turns out that's a fairly big job, better left for a snow day.
4) Of course, there's a rule that precludes players from passing on insider information.
5) The U.S. Open is going on right now through Labor Day. (Watch on ESPN2; both McEnroe brothers are announcing together!)
6) Professional tennis is constantly struggling to generate public interest in tennis, particularly now when there's a dearth of U.S. players.
U.S. Open officials have
banned on-court tweeting. (As far as I know, no one has tweeted from the court before, but they're anticipating it, I guess.) They've also posted warnings in the player locker rooms reminding players not to tweet "insider information" and encouraging them to tweet minimally.
Andy
wasn't too pleased about the insider info warnings.

Andy seems to be thinking that all tweets are public, so that sending info by tweet would be stupid because a) there'd be a public record of your rule violation and b) the info, divulged to the world, wouldn't be helpful to the bettor you were trying to feed. I suspect Andy doesn't realize that one can have more than one account, that an account can be anonymous and that one can "lock" one's tweets so that only approved followers can read them. But still, Twitter doesn't give any ability to communicate info that didn't already exist with text messaging via cell phone, except that it allows broadcasting (which is not a useful tool for betting manipulation) so I think he's right that the U.S. Open officials are being silly.
Frankly, I think the officials are missing an opportunity. I think they should instead REQUIRE players to tweet on change-overs. And require them to think of something amusing and entertaining. Tennis needs more fans.
Personal note: I follow
Andy Roddick on Twitter. As a tennis lover, I'm probably inordinately interested in things like what time he gets up, and what time he practices and how many hours he works out and what he's eating, so even his boring tweets are fun for me. Also, he has a bulldog that he tweets pictures of fairly often and bulldog pictures are always fun. He lives in Austin, btw.