So in case it isn't obvious, or you didn't check out the link to ticalc.org I posted earlier, quadropong is a simple, single player pong game where the player tried to keep the ball from hitting any edge of the screen. There are four paddles, one for each side, and the player controls all of them. To make it less annoying, two paddles can be controlled at once. Check the video:
I don't have the ball in there yet, and the graphics are sadly very basic, but the framework is there. Obviously I'm using cocos2d to speed up the process of building this app, and it has been an amazing help. There are tons of tutorials and resources available for beginners and experts alike. Two notable websites that have helped me in the last few days are Ray Wenderlich's blog (http://www.raywenderlich.com/) and Mohammad Azam's article (http://www.devproconnections.com/article/mobile-development/create-iphone-game-cocos2d-framework-136107). Both sites are a great starting point for cocos2d.