If you would like to help pretest Emacs releases to assure they work well, or if you would like to work on improving Emacs, please contact the maintainers at emacs-devel@gnu.org. A pretester should be prepared to investigate bugs as well as report them. If you'd like to work on improving Emacs, please ask for suggested projects or suggest your own ideas.
If you have already written an improvement, please tell us about it. If you have not yet started work, it is useful to contact emacs-devel@gnu.org before you start; it might be possible to suggest ways to make your extension fit in better with the rest of Emacs.
The development version of Emacs can be downloaded from the CVS repository where it is actively maintained by a group of developers. See the Emacs project page http://savannah.gnu.org/projects/emacs/ for details.