Fair warning -- I did a reset from my iPhone, choosing "Erase All Content and Settings" before returning my defective phone. The phone warned me it would take an hour, so I falsely assumed this would wipe all the data, not just unlink it. When I got to the Apple store, the tech plugged in my phone and showed me the blackra1n icon still on it.
Fortunately, I told him I had only installed it because the phone was broken and I read a thread that connected blackra1n with a "no service" fix -- which is true (I now know that was a pointless pursuit). I also told him I had no use for an unlocked phone since I had just re-upped my 2yr contract (I've since read Wireless' 6 reasons to jailbreak article). The tech said he would just erase the phone so my warrantee won't be voided. If you're reading this, don't try to fake this argument yourself because I doubt it will work if you're not sincere.
The moral is that restoring from the iPhone doesn't actually wipe your content, as one might think! Very disturbing. I hope he really did erase the phone as he said allowing others access to my email, for example.
This begs the question -- can I really depend upon iTunes to wipe my phone when it does the restore?