I have actually gotten service at the Genius bar for an issue unrelated to jailbreaking (hardware issue, home button was failing to register a click ~20% of the time) while my phone was jailbroken. During the appointment the genius noticed it was JB, made a veiled reference to it and continued to service my phone (eventually got a replacement device).
The genius bar is no stranger to phones that are JB and I've noticed over the last several years, they are usually ok with servicing a JB device much more often than in the early days (I've been on the iPhone train since the original...)
Just thought that had some relevance and was worth sharing.