Ok, here's the plan. It's ambitious but achievable, and worth it. (And it shouldn't drive prices up, either.)
Servers will work in pairs, though the implementation will allow for trios, etc. They will both serve web pages as well as take new posts, comments, etc. The servers will automatically sync with each other in real-time on a peer-to-peer basis, so they'll be capable of operating independently if one of them goes down or they get separated, and they'll automatically sync up as soon as they can talk to each other again. (Each server will have a sync daemon which stores all updates with a revision number; when a server reconnects it will just ask for all udpates from the last revision it knew about — this will ensure smooth resyncing.)
Reports will be generated by an off-site server, taking the load off of the web servers to ensure that report generation will never bog them down. (I'll have to get a feel for how quickly I'll be able to process the reports, but it might be reasonable to get the processing up to every 2 hours, which would be really nice.)
All of the servers will be DNS slaves (listed in the master record) so that there won't be any single point of failure. DNS will hit the two servers in round-robin fashion.
As I said, it's ambitious, but it will result in a system with no single point of failure that should be able to incorporate new servers quickly and seamlessly. Getting this done is going to be top priority here at Powerblogs. The transition to the two redundant servers should be completed within two weeks.
I'll keep you updated.