Gigatweet keeps running tally of total tweets.
Former Current Media executive Robin Sloan appears to have posted Twitter's 5 billionth tweet, in the form of a reply to another user that otherwise read only "Oh lord."
A third-party app called Gigatweet has been measuring the service's total tweet count for some time now, and last week some onlookers picked up on the fact that it was getting awfully close to 5 billion.
That said, Twitter's engineers have bumped up this number at least once or twice, and who knows how many test tweets were sent out in the company's early days.
But Sloan's tweet, which he has nicknamed "The Pentagigatweet," does get at least some landmark status because it actually has the number 5,000,000,000 in the URL. The number at the end of a tweet's URL is apparently the running count of tweets that have been posted until that point.