In the upcoming version of LM-X, we've extended Mac OS X support to include the x64 platform. The nice thing about OS X is that it offers what Apple calls "universal binaries." Essentially, this means that we can package multiple platforms into one file that will work on a number of platforms at the same time.
This is very convenient and makes it easy to provide the x64 support.
This is what our JNI (Java Native Interface) library looks like, with all the supported platforms:
sh-3.2# file liblmxjava.jnilib
liblmxjava.jnilib: Mach-O universal binary with 3 architectures
liblmxjava.jnilib (for architecture i386): Mach-O bundle i386
liblmxjava.jnilib (for architecture ppc7400): Mach-O bundle ppc
liblmxjava.jnilib (for architecture x86_64): Mach-O 64-bit bundle x86_64