OS X 10.8 with XCode 4.5 tools
Here is the build log:

[exec] gcc -dynamiclib -o /Users/zeiglerr/Code/jna/build-d64/native/libjnidispatch.jnilib -framework JavaVM -compatibility_version 3 -current_version 3.5.0 -mmacosx-version-min=10.3 -install_name libjnidispatch.jnilib /Users/zeiglerr/Code/jna/build-d64/native/dispatch.o /Users/zeiglerr/Code/jna/build-d64/native/callback.o /Users/zeiglerr/Code/jna/build-d64/native/libffi/.libs/libffi.a
[exec] ld: warning: could not create compact unwind for _ffi_call_unix64: does not use RBP or RSP based frame
[exec] Undefined symbols for architecture x86_64:
[exec] "_objc_msgSend_fixup", referenced from:
[exec] l_objc_msgSend_fixup_autorelease in dispatch.o
[exec] ld: symbol(s) not found for architecture x86_64
[exec] collect2: ld returned 1 exit status
[exec] make: *** [/Users/zeiglerr/Code/jna/build-d64/native/libjnidispatch.jnilib] Error 1