[Flow]

   iMac:~ Flow$ ioreg -l -p IODeviceTree | grep firmware-abi
       | |   "firmware-abi" = <"EFI64">
   iMac:~ Flow$ 

EFI64 means ok for ML.

[mturmon]

And the reverse, not OK for ML, looks like this:

    % ioreg -l -p IODeviceTree | grep firmware-abi
        | |   "firmware-abi" = <"EFI32">

on an old (white polycarbonate) iMac.

[Flow]

As long as your CPU is 64-bit it seems one can use "hackintosh" techniques to run ML anyway.