Primarily touted as a replacement for the AMPS analogue network - the main selling point being a CDMA phone can work further away from a base station than a GSM one. Other side benefits being CDMA doesn't interfere near as much with radios, hearing aids, and the like.

CDMA doesn't necessarily = fast though. I believe the current CDMA networks here offer 14.4K data rates. (No idea ATM which flavour of CDMA this is called). 'Til 3G comes along of course.

.au has CDMA<->GSM SMS interoperability between most, but not all, carriers,