I flashed 2 ant S3's with the latest firmware antMiner_S320140826; after flashing they both started hashing at around 100GH/s. Went back to antMiner_S320140721 which works fine (~440GH/s).
You *must* choose a frequency in the Advanced Options of the Miner Configuration, otherwise it will default to 100GH/s. If you forget that step, you'll get only 100GH/s and you'll show no frequency in that column on the Miner Status page.
You're not the only one - this has been discussed here since about the time that the second-to-last firmware update was posted. ;-)