Haven't got time to troubleshoot it but putting SP2 on blocks iTMS. Take it off... ta da! iTMS comes back. No difference between Mac or PC. Firewall client or no client. Proxy or no proxy. Created explicit don't cache rules for phobos.apple.com et al. Created let *everything* through for those IPs rules. Nope. Nada. Overall the firewall seems to be slower too. I'll wait for a few more hotfixes before re-applying it.