I'm currently doing mainly Ruby on Rails development. My preferable requirements would be to get at least two code editors or one code editor and a terminal side-by-side. It should be portable. I've already dropped off 17" MBP, because it's simply too big. 11" MBA is too small. Both, 13" MBA and 15" have 4GB memory and both can be upgraded to SSD. My main concerns with MBA 13" is the Core2Duo processor and 1440x900 resolution. Will the screen size be enough? Processor speed is probably the bottle-neck in RoR development, so will I save a lot of time with the Intel i5 that ships with 15" MBP? Oh, and no matte screen option. On the other hand, 15" has almost twice the weight as the 13" MBA. But it can be purchased with the wide-screen matte display with 1680x1050 resolution. And it has the i5 processor. I would be very grateful to hear any comments and recommendations by developers who have experience with this kind of development on MacBooks.