If you’d like to join App.net for free, this link is your huckleberry. There are 100 invites attached to that link, so sign up quickly if you’re interested.
I’ve been finding App.net making it’s way into my social stream more and more these days. With the folks I’m following, I’ve seen engagement ramp from around 5 posts/day to 25-30 posts/day – seemingly overnight. It definitely has that “early Twitter” feel at the moment.
I’ve been looking into some of their technical bits too because I’ll probably create an App.net Tools plugin for WordPress to enable the same “post here, participate there and my data is my data” workflow I use with Twitter and Facebook.
The recent implementation of two-factor authentication is quite nicely done and my experience asking questions in the developer Patter room was extremely positive.
Give it a try, see if it’s for you.