Hmm. There seems to be a clash between anonymity and usability here, as is so often the case with security systems.
Perhaps we could allow admins to see part of the reverse DNS, but not all of it. If we strip off the last two parts of the name (in this example, leaving just "manc-cache-5.server"), we'd get something that nine times out of ten would identify a proxy or not, but would not be personally identifiable.
Reasonable?
In most cases we find out pretty fast and there are/were a few editors who I know if I block I'm going to have to kill the IP block. personaly I can't see the point of the ipblock at all.