Brian, thanks for taking the time to write about this. It's so important and, at the same time, such a pain to understand and implement properly.

I have recently come across the problem while trying to make reporting services talk to an analysis services instance through Windows integrated security. In the past we have circumvented the double-hop authentication issue by configuring reporting services (and linked servers) to talk to the destination datasource through SQL authentication. However, in doing so we have compromised security. Also, with Analysis Services, SQL authentication does not work, so now we are forced to make Kerberos work.

You have really felt the pulse of the community with this one.