I am currently looking a lot into git-flow, and trying to figure out, how to use it for the projects I am involved on.
I have looked at the various git-flow tutorial
More on "git-flow improved":
https://plus.google.com/109096274754593704906/posts/R4qkeyRadLR
The key is to start features from the point of last release. Whether you have 1 or more supported versions that are published should not be an issue.
UPDATE:
I have it rewritten - in blog form:
http://dymitruk.com/blog/2012/02/05/branch-per-feature/