As part of our research (to be detailed later) we forked a random nightly of Safari 3.2-era WebKit, and made some various modifications. A few months ago Snow Leopard came out, which is OS X 10.6 for those of you not keeping track. This new OS version only uses Safari 4.0; this led to several difficulties in trying to compile and run Safari 3.2 against OS X 10.6 SDK.
Eventually, I found out that you can retarget development against specific OS SDK's. Thus the solution to the problem was in effect to cross-compile downwards to 10.5 on my 10.6 machine. After most of yesterday spent recompiling WebKit with various combinations of flags, I can finally run our research project on my personal machine.