It's exciting to hear that you're looking at building an App.net module for Spring Social and I'll be happy to help out as much as I can. To get started, you should read http://static.springsource.org/sprin...lementing.html if you've not done so already. You may also look at some of the existing modules such as the Facebook or Twitter modules to see how they're done.
If you're wanting your project listed on the Spring Social home page among the other community-led projects, all you gotta do is ask. There's no such thing as an "approved" implementation and I link to and help promote any and all community-led projects such as yours. I've already added a link on the Spring Social homepage and, unless you don't want me to, I'll tweet about it tomorrow morning. (It looks like you're in Israel, so it's almost Friday morning for you, but I'm in Texas so I've got about 10 hours before my workday starts...I'll tweet about it then.) Maybe by promoting it this way you'll find some others out there willing to help you out (and enable you to remove the "only developer" line from your signature).
Let me know if you have any questions and thanks for contributing to the Spring Social community!
Spring Social Project Lead