There've been some reports about an upcoming "Twitpocalypse" in which Twitter would finally crash and burn due to the limitations of a 32-bit signed integer. Allegedly, Twitter will collapse once the number of tweets passes 2,147,483,647.
Unfortunately, it doesn't look like the Twitter revolution is going to die out as soon as I'd like—there are reports that the "Twitpocalypse" rumour was started as a joke, and multiple Twitter clients are announcing that they'll be just fine. There are, however, reports that some individual clients, including the iPhone app Twitterific, are down, but as the number of tweets has now passed the crucial 2,147,483,647 mark mostly unscathed, it looks like Twitter has survived to annoy me another day. [CNET]