I am setting up a Disaster Recovery site in our Calgary plant. Our current, live data centre is in Vancouver. This is to be what I would call a "warm" site. The servers there are to be accessible, but not hot-synched with the real world.
My idea is to have a live, running Exchange 2003 server that is in the same administrative group as my live Exchange servers. The idea being that if a disaster hit my data centre, I would have an Exchange server alive and ready to go. Then, I would recreate the critical mailboxes on that server (granted, none of their old e-mail would be there) so that they could start communicating right away. Then, I would have time to do a proper restore on the old box or replacement box etc.