Hi,
Found a perl (!) SIGTRAN stack on the net, thought someone here might be interested. Includes a very basic HLR emulator and various other bits. Looks fairly easy to extend to send/respond to various GSM MAP messages, could be useful for testing.
http://mtve.livejournal.com/13725.html
http://frox25.no-ip.org/~mtve/wiki/SigTranSol.html
Enjoy!
Duncan