I need run Mac applications on a remote Mac machine and display it on a local Linux machine's X server (a lot of articles on the Internet seem to be detailing how would you do it the opposite way).

$ ssh -X mac-box
$ cd /Developer/Applications/Xcode.app
$ ./Contents/MacOS/Xcode
Sat Oct  3 20:41:26 mac-box.local Xcode[15634] <Error>: kCGErrorFailure: Set a breakpoint @ CGErrorBreakpoint() to catch errors as they are logged.
_RegisterApplication(), FAILED TO establish the default connection to the WindowServer, _CGSDefaultConnection() is NULL.
^C

1. My $DISPLAY variable appears to be empty. What should it look like so that forwarding works correctly?
2. Can I run OSX applications this way at all?