1. 3D Graphics Chip
A built in 3D graphics chip will enhance graphics, hence bringing the iPhone gaming experience to a whole new level. Is this what our iPhone games will look like? One can only hope.
2. Enhanced Bluetooth
The purpose of enhancing bluetooth is so that game developers can release add-on products, such as keyboards, controllers, and joysticks, for their iPhone game. The chances of this actually occurring are slim. (How many people can you actually picture sitting there with their iphone with a joystick attached?)
3. "A new, higher-speed network"
There's a popular rumor floating around about the new iPhone having the capability to run on a new, higher speed network. While this would improve gaming by allowing users to play multi-player games without being on the same WiFi network, what "network" is this rumor referring to? The current 3G network hasn't been perfected yet, and there is no way that a new network has been developed and hidden until the release of the new iPhone. But rumors will be rumors.