Hi Matt, congrtulations. It sounds very cool!
As for releasing it....there are many options. We have a very active community here. Most developers tend to just start a new thread in the plugin forum announcing their new script. Then you can either upload your script directly into that thread, along with the pdf documentation. The benefit of doing it this way is that you get a lot of users who chime in with bugs and glitches and requests. The bad part about doing it this way is that you get a lot of users chiming in with bugs and glitches and requests

J/K. Prolly the worst thing about uploading it here directly is that its hard to do any version control or true collaboration if that is what you want.
Jim has recently been using github maybe? We've used google code for a few open source collaboration projects. So far none of these open source SU projects have really taken off though.
So for hosting, put it wherever you would like. If you host it here, just make it clear that its meant to be open source and improved upon (and you might or might not get any collaborators). Or host it on a version control collaboration site, and just link to it from here. Either way, congratulations. It sounds really cool!
Chris