These are the release notes to the gsch2pcb tutorial.
ERROR: Unbound variable: open-output-pipe
then the problem is syntax in gnet-gsch2pcb.scm that worked in guile 1.4 but does not work in guile 1.6. You'll need to upgrade to using at least gsch2pcb 1.0.1 to solve this problem.
The tutorial was originally prepared by Bill Wilson (bill–at–gkrellm.net).