If you are helping the Python developers by testing the 2.6 or 3.0 releases, you will want to download the latest alphas: Python 2.6a3 and Python 3.0a5. The usual caveats apply: Don't use these in production, just testing. If you want to see what's new in each release, check out the bugs file: 2.6a3 and 3.0a5.