I saw that guide. Putting in a bogus DNS server IP address would probably work, but at that point I wouldn't be able to get game updates.
Basically my concern is that if my PS3 is connected to the net and Sony decides to do something drastic because of the jailbreak, like forcing an unprompted firmware update, my PS3 would get updated.
I am using the proxy with 3.41. I Just can't tell if my PS3 realizes it. In 3.15 I could tell my proxy was working because I couldn't connect to the PlayStation Network. But in 3.41 I can connect to the Playstation Network with the proxy active. This is what makes me wonder if with 3.41, firmware checks and so on are happening outside of my local DNS redirection for *.update.playstation.net, therefore leaving me vulnerable to firmware updates.