This is so far from a secret it's not even funny. Imagine if we'd only just discovered what those two pins on the connector did?
Hell, even the breakout board the guy (who's original, non full page ad-encumbered article can be found here) bought has the bloody serial pins labelled.
It's not remotely surprising that an embedded device has a UART on it. It's even less surprising that a device designed to interface with very simple dock devices has a UART exposed via its peripheral connector.
What is surprising is that the combination of breakout board and RS232 line driver somehow managed to be bigger than the phone.
"It's like taking a desktop and putting it in your pocket," said [VP of processor marketing — Eric Schorn], and it was clear that he considers this new design to be a pretty major shot across the bows of Intel and AMD. In case we were in any doubt, he turned the knife further: "The exciting place for for software developer graduates to go and hunt for work is no longer the desktop."
We don't really understand it, so we'll give it to the programmers.