If you are comfortable with PHP and would like to participate in the testing portion of our development cycle and report bugs you find, beta or CVS releases might be for you.
By their nature these releases are unstable and should not be used anyplace where your data is important. To hear about the latest beta releases your best bet is to watch the development blog and the beta forum, and you can also sign up for our beta announcement list.
Join our Testers list to keep up on the latest and greatest broken beta version of WordPress.