The new Google Mini appliance will support Active Directory. The support for AD will be available in the 2.2 version of the appliance which releases next week. Adding the support for AD makes perfect sense. If you're going to index documents in a corporate network you need to support AD.
I understand that it will also serve up results based on your own identity/authorization. So, you may search for "Quarterly results" and it may have 50 search results for this term but if you don't have access to those directories or files then the Mini will not serve up the results to you.
This implies to me that it is caching the ACLs. Hmmm, interesting. I can see a lot of potential here. If I was an administrator or, even better, an application, how could I access that ACL cache? Assuming Google knows how to search (!) wouldn't it be great if there was a complete enterprise ACL cache out there that is searchable? If Google Analytics could report on the ACL cache? If Google Analytics could show the changes over times, the changes to a file or directory's security settings, answer questions like "What files does Jackson have access to?", etc.
The "Google Compliance Appliance"?
Google, Active Directory