Contributing to nose
You'd like to contribute to nose? Great! Now that nose is hosted under Mercurial, contributing is even easier.
Get the code!
Start by getting a local working copy of nose.
Next, if you plan to push changes back to the core repository, you should set up a public repository of your own somewhere. Bitbucket is one good place to do that. Once you've set up your bitbucket nose repository, pull from your working copy of nose core, and push to bitbucket. That (with occasional merging) will be your normal practice for keeping your repository up to date.
Join the nose developer list at google groups. It's low-traffic and mostly signal.
What to work on?
You can find a list of open issues at nose's google code repository. If you'd like to work on an issue, leave a comment on the issue detailing how you plan to fix it, and where to find the Mercurial repository where you will publish your changes.
Actually, I want to work on the python 3.0 version
The python 3.0 version of nose, nose3, is hosted at bitbucket. You can clone the repository from here:
hg clone http://bitbucket.org/jpellerin/nose3
If you plan to contribute changes back, you should fork the repository on bitbucket.
Issues affecting nose3 should likewise be reported at the bitbucket site, not at google code.
nose3 hosting may move to google code at some future date, when or if google code supports bitbucket-style forking.