Just to start off...Apple Computers makes the Mac. Just a little pet peeve, no harm intended.
Mac OS X is based off FreeBSD (10.0 was BSD 4.2, 10.2 is BSD 4.4, 10.3 is BSD 5.0) which is Unix. Basically all Linux, Unix, Java, Mac OS 9 and Windows app run nicely in their various incarnations...