Since there's nothing better than this 'Describe the new page here.' here now...
It doesn't appear that there are snapshot builds of jetspeed available. The way to get the software running is to grab a copy from CVS by following the instructions on the cvs usage page at http://portals.apache.org/jetspeed-2/cvs-usage.html
Then, follow the getting started guide to get things moving (http://portals.apache.org/jetspeed-2/getting-started.html). Be sure to get a copy of all the software dependencies first. If you don't have tomcat already, go with 4. 5.x support is still a little flaky in my experience (mostly due to tomcat issues)...