If you take a close look at the control board, you may notice a small uFL connector on the upper right hand corner of the board. If this connector is wired up, and the firmware supports it, it would be pretty easy to add an uFL to SMA cable to wire up an antenna! This would be good news for people like me who need wifi.
Wifi works. Check it out:
I don't know if this has been mentioned yet... but the S3 has wireless. I've got mine in hand, saw the wifi tab, figured I would try it out. Bam!
So, while I don't see any place to hook in an antenna, having it sitting right next to my router, that's kind of irrelevant.