Russel,
they have a custom ASIC chip which gives better signal pickup than the old chip.
This means better signal response, more so if paired with the new Rev L TIU which also has a new ASIC.
Actually, the digital signal processors (DSPs)in the PS3 engines and Rev. L TIUs are not ASICS (application-specific integrated circuits), as were the DSPs in the PS2 engines and earlier TIUs.
The PS3 engines and Rev. L TIUs have FPGAs (Field Programmable Gate Arrays) that are faster than the ASICs, allowing PS3 engines and Rev. L TIUs to "listen" better for commands and acknowledgments.