Not to Mac, but cross platform includes between AMD and Intel or even between a P3 and a P4. Unless someone can establish that the floating point units behave _identically_, you will have to use Blizzard's floating point emulation library for arithmetic. Alternatively, you can write float<->double routines in integer arithmetic and do all the FPU work in double precision.
Blizz FP emu Doc
Single player stuff is of course okay.