I just noticed this on the bitmain site:
https://bitmaintech.com/files/download/antMiner_S320140811.binThe notes just say "added advanced frequency" which means there is an extra tab for overclocking in the miner configuration page...just flashed now thought I would give a heads up to you all

Edit: in order for the frequency and firmware to work and not come up blank, I used the "save settings" box when flashing the firmware, then after the flash is complete and the miner has rebooted, go to the miner config/advanced tab and hit apply on the frequency you want (it defaults to 237.5 and no idea why 100 is in there), then hit apply on the main miner config page to be safe, then reboot the miner...works for me!
so, basically, on current miners (at least B4-7) 237.5 is a de facto default. I thought so....
I can't speak for batch 7 as its not even shipping yet and I only ordered batch 2,3,4,5, and 6, and batch 5/6 came with july 28 firmware which was nowhere to be found
The firmware defaults in the dropdown to 237.5 but I don't think its actually using that as when you check the miner status the frequency stays blank unless you do what I outlined above...and also it does not read the original asic-freq file for this dropdown list...haven't had time to see where its hiding now...yet.