Twitter userbase growing faster than expected

On January 6, 2008 I predicted that Twitter would reach 1 million users (with a public profile) before April 1, 2008.

I have been tracking since then the number of Twitter users as reported by Twitdir. It looks like Twitter's userbase is growing faster than initially estimated. The dotted line on the graph below shows the estimated growth, the solid line the actual number of Twitter users. I have no doubt that the 1 million user mark will be reached before March 1, 2008.