Ajato is still in heavy development. So, every pre-1.0 may bug very very buggy or not work at all.
We plan to launch a new version every month. And a beta version by July 2008 (when Ajato will complete one year).
If one month is just too much it to you, and you want the newest code now, you should go to developers zone and see how to use the Bazaar versioning system
See the list of releases here