Userland debuggers are currently broken by the XOR cookies. They will not be able to backtrace since the in-core return pointers are obviously distorted. The in-kernel core dump mechanism may be able to walk the stack and cleanse each activation record in the program. Further research must be done. Threaded programs would present an additional beast for reasons outlined above by the kernel return stack.
Debugging via Ptrace() will also present problems for the parent processes since the in-core program counter will have been modified by StackGhost.