We have recently finished a migration to Exchange 2010 from Exchange 2003 and removed our Exchange 2003 server. We have four conference rooms that were set up as resources in 2003 and worked properly as far as when you created a meeting with that as a resource it would either book the meeting if available or tell you the room was unavailable.
Since removing Exchange 2003 this feature no longer seems to work. The rooms have been converted to Room Mailboxes, and the Enable Resource Booking Attendant feature is flagged to be on. I have myself set up as a delegate and "Forward meeting requests to delegates" flagged on, but I don't receive any.
On resource In-Policy Requests and Resource Out-Of-Policy requests I have All users set for all three features, and have added all users to have Full Access permission, but when I book a meeting, the room doesn't add the meeting to it's calendar nor notify the user that the resource was booked (or if the resource is unavailable.)