As of right now, the App.net page on Facebook has 74,066 likes. I have a feeling that a lot of those people will jump on board if it's anywhere close to the goal in the last few hours.
The biggest problem with app.net right now is its diversity.
The 40 members shown in the App.Net community section when I went to the Join page are ALL 20-40 year old, white males. Not a single female or non-white.