First please read the two links within http://www.zenphoto.org/pages/get-involved
Then there are basically two ways to contribute generally:
1) Provide the tools you create as 3rd party tools. This is actually the preferred way.
2) Use GitHub's issue tracker or a pull request. Be sure you use the 1.4.5 build for what you do. Sbillard will decided if this is added. But since it would be a new feature it will most likely not get in before 1.4.5 anway. (1.4.4.x are support builds only and do not introduce new things unless needed because of bugs or security issues).
