Developing with Eclipse, Visual Studio .NET and Xcode - 13“ or 15” Macbook Pro? (Or AIR?)
In case anyone is reading this now, the 13" Retina screens can be put into a higher-resolution scaled mode 1680 x 1050 mode which is still readable. It's the same as the Macbook Pro 17" I used to use, just in a smaller space.

This is ample width for using XCode or other IDEs