It looks like Microsoft released a new Xbox360 Slim motherboard codename 'Corona'.
This new motherboard was found in a Forza 4 250 Go Pack with black matte finish, a Liteon 1071 ODD and 2011-08-17 MFR. The PSU goes from 10.83A (for the orginal 'Trinity' Slim motherboard) to 9.86A.
The biggest change it that it looks like the HANA chip is "gone". It is suggested the HANA and SouthBridge have been put together into 1 chip on this new motherboard. This could have (serious) implications for the Reset Glitch Hack (RGH) as it was using the HANA chip for the timing management (but there might be alternatives). But at this time it's too early to tell. However it is (very) unlikely this is a answer from MS to the RGH ... a motherboard revision takes months of preparation and this motherboard was manufactured before the RGH was even released.