The day the tweets died: Twitter goes down because of an attack

On Thursday, Twitter.com was down for about two hours. In the past, the site has shut down service for upgrades or repairs; this time, the shutdown was not planned.

"The site is back up, but we are continuing to defend against and recover from this attack," Twitter wrote on its status update blog after 11 AM EST. "We are defending against a denial-of-service attack." Even so, over an hour after Twitter said that the site is back up, many folks are still unable to get it working.