Update: The PM8200 has a higher resolution display (132×160 vs 120×144 on the 8100), and a newer WAP browser (NetFront 3.1 vs 3.0 on the 8100).
The Sanyo PM8200 will be an improved version of the 8100, but we now have much more specific details. The PM8200 will have ReadyLink, and SMS, as well as improved RF and battery life.