Message from IRC channel, the Motorola Crystal Talk will be a built-in feature in CM7 for Milestone A853 (RC13) and Defy MB525, all code work is done by Quarx2k, many thanks to him, now the code is under final improving, people who does not want this Crystal Talk function could disable it in the settings.
I have not had a Defy to make a call, but wiht Milestone 1, I really enjoy the Crystal Talk reducing the noise when I make a phone call, I have used to switch the phone with my gf, then she called me on the crowded bus, when I pick up the phone I can not believe that her voice is so clear. After that day, I was used to add Crystal Talk update patch to every CyanogenMod 7 for Milestone roms. As people said, a reason for buying a Moto phone is the Crystal Talk.
So an update rom will roll out later today or tomorrow, CyanogenMod 7 RC13 for Milestone A853 and CyanogenMod 7 for Defy. Will post the downlink and review when it is available.
Some people have asked whether it is possible to patch the Crystal Talk function to other phone like HTC or Samsung phones, I think this feature needs a special electronic design into the phone main board, and two native microphones, so it should be only work on Motorola Android phones.