Apple threw a bunch of bogus references into iOS 5.1beta1, but that didn't stop developers from uncovering references to real devices. In between the garbage, there's a reference to the iPad 3. Each reference has a device id of 1, so we know it points to an actual device. Finding the iPad 3 isn't all that surprising as we have seen similar references before. This discovery is just another piece of evidence that suggests Apple will start selling the tablet this spring.
What's missing from this config file is a reference to the iPhone 5. This doesn't mean there won't be an iPhone next year. It only means the handset's launch is farther off than the iPad 3 and references to it in the underlying iOS code are not yet necessary.