While all previous iPhones and iPads have supported wired data transfer over 30-pin or Lightning connectors at USB 2 speeds, the newly-released iPad Pro is apparently capable of more. During its recent teardown of Apple's latest tablet, iFixit discovered a USB 3.0 controller on the Pro's logic board.
Additionally, there will apparently be adapters to allow data transfer at the higher USB 3.0 speeds, though a timeframe has not yet been established, according to Jeff Carlson:
I just confirmed with a source at Apple that there are forthcoming adapters that take advantage of the USB 3 speeds, but they aren't yet confirming when they will ship. That's bare-bones Apple-ese for "Yep, and you'll find out more when we're ready."
USB 3.0 has a maximum transfer rate of 5Gbps, about ten times faster than the maximum transfer speed of USB 2.0. Whether the iPad Pro will be able to take advantage of USB 3.0's full potential remains to be seen, but it's nice to see that Apple is making progress in this area.