I currently use a Mac Pro for Xcode development, but am considering buying a MacBook Air when the newer models are released.  How should I collaborate with myself when using both machines on the same project?  Should I use Git, or should I just acess the Mac Pro as a networked drive from the MacBook, or something else?
One Developer, Two Machines
version control;ios;osx;xcode
You should definitely use a SCM system, even when only working on one machine. Which one you use is not that important. I would also recommend keeping the working directories on the two machines separate rather than using a directory shared across the network. Less chance for cluttering your environment, and allows you to work when the network is unavailable or down.