New Post: Using GIT for Source Control and Community Code Contributions

I second the opinion to keep it simple. I wouldn't spend too much time thinking about branches, build or migration. You can look at the way jquery has its repo setup, https://github.com/jquery/jquery, they are obviously quite experienced with this.

Create a repo on github (or codeplex) and drop the unminifed file there. You may have a structure already in place, something like this isn't uncommon:

vendor
  jquery.js
src
  spservices.js
readme.md

Don't name the files with version information in them, that is what the source control system is for. You use branches and tags for versions, but again, don't spend too much time thinking about this ahead of time, you cross that bridge when you get there. If you look at jquery's repo and expand branch dropdown, you can get a sense of how they are utilizing it.

I know codeplex supports git, I haven't used it. I have used github for source control and codeplex for documentation. On my github page I only say to go to codplex for docs. I am not sure how I feel about it, this was dictated mainly by the fact that the sharepoint crowd tends to be more likely to look on codeplex then on github. That may not be true anymore though. You have a much bigger fish to fry with your project and you have a much better sense of the user base and their preferences.

Hope that helps.