Well, it looks like non-Tesla owners are out of luck when it comes to using Superchargers. I heard they check the VIN when you connect, and if you're not a Tesla owner with the lifetime charging perk, you're SOL. It's a bummer, but I guess Tesla's trying to protect their early adopters.
They're running a pilot program in a few countries, allowing non-Tesla owners to charge at select Superchargers. Hopefully, it goes well, and they'll eventually open them up to everyone. Fingers crossed!