Indeed. I keep seeing these sorts of posts all over the place today... "Ohnoes, App.Net doesn't have millions of users yet - it's a failure." Rubbish. It's been around a month or so, and is only really known in tech-circles at the moment. They have managed to convince a significant number of people to sign up for a service when they can access a larger competitor for _free_. That in itself is a pretty big success.
It's too early to call App.Net a success or failure. Maybe it got too much press too early, and that has given people unrealistic expectations? I say come back and look at the numbers in 12-18 months. Then we'll be looking at a mature service, and will know how many users they added, or convinced to renew their subscription.