Re: Macbook or Macbook Pro ?
I develop on a G4 iBook 1Ghz 12" screen, with a 22" screen plugged and firmware patched with Screen Spanning Doctor for real extended desktop. I love it.
12" is enough for light dev while you are in a train or in a waiting room. I find the MBP are way overpriced specially when you compare to portable PCs. I recently bought an HP 17" with Core2Duo Centrino T7250 and 2Gb DDR for only $750... okay it can't run Leopard, but Apple hardware prices are too high.
But yeah, nothing can beat Rails dev on a Mac.