Only OSX 10.4.0 I can run test_tk:

rdmurray@buddy:~/python/py3k>./python.exe -m test.regrtest -uall test_tk         
[1/1] test_tk
Thu Oct 21 12:41:16 buddy.home.bitdance.com python.exe[93560] <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.
1 test OK.

But test_ttk_guionly crashes with the abort trace after printing the above.  I presume this means test_ttk_guionly was factored out at some point after this issue was raised, but it is interesting that test_tk produces the warning about the window connection but only _guionly crashes.