Update: It appears to be a problem with Verizon iPhones (from what i've seen on Apple's discussion boards). After connecting the phone to my computer though, iTunes offered the non-beta 6.1 update and installed the update successfully.
I'm wondering the same thing, why is Apple pushing a Beta on non-developers? Wait a minute, isn't Beta 4 supposed to have expired yesterday? Why would they be pushing an expired Beta now? Must be something wrong on their end.