Hi Ziad,
I do not think the 10.7 binaries are openMP enabled, as I am using them now.
The activity monitor for fnirt, for example, does not go over 100% CPU usage, which is seemingly limiting it to one core.
I know in SPM that the registration/warping step is multithreaded, so I would assume that this would definitely be the case here.
I assure you that, from what i have seen, the compiled 10.7 binaries do not use more than one core per process.
FYI: I had to manually put in the -fopenmp and -DUSE_OMP flags in the $CCEXTRA alias, because if I did not, make does not compile with openmp by default as you would expect.