You could write your own [link|http://www.google.com/apis/|Google Web Service] client, put it up on a site and access the groups that way. You would be limited to 1000 queries a day though. Also, I don't know if they provide the groups via the API.
D'oh! I guess not. From the FAQ:
2. Can Google APIs be used to access Google Groups? Image search? Directory search?
No. The Google Web APIs service can only be used to search Google's main index of 2 billion web pages.