Hello,
at the moment you can get them using euca-describe-availability-zones verbose if you run as admin (not as user). At the moment in the AWS API this information is not specified: the user just knows from the documentation what the various instance types are.
Nice to hear you are getting a UI for eucalyptus: let us know when you have something and we can add you to the list of client tools which support eucalyptus.
cheers
graziano