If I were to buy a new iPhone and get AppleCare on it, would it void AppleCare the minute I jailbroke? Or can it only be voided if I were to take the Jailbroken iPhone to the Apple Store for repairs/replacments?
It would void the warranty while you are Jailbroken however, you can just restore your iPhone before sending it in. Apple have no way to find out if it had been Jailbroken.
Yeah that's what I'm thinking. Like what I'm asking is does Apple automatically void my AppleCare when I jailbreak? Or can I still get AppleCare service as long restore via iTunes before I take it to the Apple Store?
Not.
If its broken and wont restore with itunes then it will just error out and be stuck at the apple screen.
It wont even boot if it gives you an itunes error and the restore does not fully complete.
So if it has a hardware issue no one will be able to get into the home screen and see if it was JB or not.
I am sure that if Apple wanted to someday, they could have some sort of background process running to detect a jailbreak, and then phone home to void your warranty. They haven't done it yet... but it is completely possible.