Celebrity Twittering seems to be at an all-time high, which means it's time to brace for the inevitable comedown, when the fickle famous give up microblogging forever. Oprah Winfrey, ever the trend setter, is leading the charge.

Arguably Twitter's most famous adopter, Winfrey hasn't posted to the service in more than a month. Her Twitter run lasted less than two months, but who can blame her? With a daytime talk show and magazine to run, a close connection to the White House and access to Broadway and Hollywood premiers and celebs, why bother with the banality of 140-character status updates?

Winfrey did just have a 10-day birthday cruise around the Mediterranean, but hardly explains her 33-day Twitter absence. It's possible a long summer break could explain musician Dave Matthews' 24-day Twitter absence, but what's the point of a vacation if you can't rub your friends' virtual faces in all the fun you're having, via Twitter?

At least Oprah and Matthews still have their accounts; Secretary of State Hillary Clinton outright deleted hers sometime after October, when she was still on the celebrity Twitter lists. Like Vice President Joe Biden, who hasn't posted to his personal account since August, Clinton is now tracked by a mysterious, impersonal "UNOFFICIAL TWITTER."

But of course, being on Twitter isn't any of these people's jobs. Not so with Jennifer Preston, the New York Times' Social Media Editor., who was called out this morning (by new-media zealot Jeff Jarvis, naturally) for going a full month without tweeting. Well, we kinda should have figured: Preston only recently unlocked her tweets, then promptly declared she's be "listening more than tweeting," while figuring out how to clamp down on tweeting by others.

But you can't even pay some people to tweet, is the point!

(Top pic via)