Not so. NTT DoCoMo and KDDI, two of the three operators in Japan, don't use GSM. DoCoMo uses a system called PDC which is incompatible with all other countries although their next generation service will be compatible with Europe.

KDDI, like most Korean operators, uses CDMA like Verizon and some other US operators.

So add Japan and Korea to your list of (mostly) non-GSM countries, although Japan will be changing. Operators in China, which will be the largest cellular market in the world, will ultimately be using THREE different technologies -- UMTS (roughly speaking, the successor to GSM), CDMA, and TD-SCDMA (unique to China).