Jaunty Jackalope is currently in the Alpha 2 phase as of this post, you can follow the development release schedule here
To upgrade simply Press ALT-F2, and type in update-manager -d
A message will appear informing you of the availability of the new release.
Just a note, since this is alpha it isn't suggested to run on Production machines. Run it only if you care about bleeding edge software and don't care about system crashes and your confident your data is backed up safely.
I personally use a separate /home partition so I don't loose my valuable data, you can use the site search on this site to find information on that as well :)