My work computer is a 15" MacBook Pro. Its performance is definitely good enough for serious software development, even if the Scala compiler and the IntelliJ indexer do push it at times. In fact, performance is so good that I have been wondering how Apple and Intel have managed to get that much CPU power, and the requisite cooling, into such a small machine. That is, small when compared to desktop or workstation computers.
In contrast, my Hackintosh at home now has about 800g of metal hanging off the mainboard to cool the CPU. Granted, it is overclocked, which requires disproportionally more cooling, and it is about 50% faster than the MacBook but, still, I found it surprising just how much less cooling the MacBook seems to need.