Evan Henshaw-Plath, formerly lead developer at Odeo (which spawned Twitter), dug up an old email from Noah Glass to the Twitter team, which announces, among other things:
Also. We currently have 160 beta testers. We receive about 100 status updates per day. We are sending between 800-1000 SMS per day.
After three months of running and building twitter, we only had 160 users!
I'm not sure that's the right conclusion! My take would be, if with only 160 registered users you're getting 100 updates a day, you're sitting on a gold mine. Far from being a sign of "no traction", this is a sign of great early engagement - particularly for what was essentially a social networking site, which suffers from the typical chicken-and-egg problem, and should have been utterly useless with only 160 users.
@swombat Don't get me wrong, the team was pretty excited about how much use twttr was getting. It was just small, and grew slowly.
@swombat After one month, we had an insane 100,000 messages delivered (we did real delivery via sms then) with only 100 users.