Based on them, ProgSkeet appears to utilize an Actel A3P125 IC (datasheet HERE) which is common among modchips due to its security, and offers enough address lines for at least 2 (if not more) NANDs with 16 general purpose lines and boasts 125,000 system gates with 133 maximum user I/O lines. It also offers JTAG pads, presumably used for programming the device.
Upon completion, ProgSkeet will allow users to downgrade and jailbreak their PS3 similar to the Infectus Mod along with backing up and reflashing the console's memory.
More details will be posted as they become available on the ProgSkeet project, with a video now posted below and a ProgSkeet Review for those interested.
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These devices could be very handy, not really for the end user but people who offer services like YLOD repair for a fee for those who are afraid or can't be bothered could also offer a downgrading/unlocking service.