So are you using CDMA or GSM network ? Who cares and who wants to wrorry about the network capability of their mobile device ? not me at least, and especially not those who travel abroad frequently. Iphone 4S users will not have to worry about which network they are using because it will supports both GSM and CDMA.
Why would that will matters? first , there is the business class of folks, an important market for apple, who need a device that works in whatever country they may be in this week. If you recall, Apple kicked off its "Lets Talk Iphone event by running off some impressive figures. Apple new CEO Tim Cook made it a point to mention that 93% of fortune 500 companies are testing and deploying iPhones in the workplace. With CDMA and GSM support, the iPhone 4S can roam on GSM networks in 200 countries, making it ever more business-appropriate.
Also Apple a phone with CDMA GSM support simplifies its product line and will enable it to deploy on the new carriers. Like Sprint without a second thought.
Also of course it is classic Apple to add in technology that strips out confusion for its customers. You can stop worrying about your carrier network and which iPhone model you need. And just buy and use the iPhone.