I have written a couple of very simple functions, send and receive, to communicate arduinos using the Mamba shield. I do not use interrupts but polling, so both are blocking functions. But they are really simple to use and, best of all, they work -without requiring the PLM-1 tricky code.
Let me know it you are interested and I will publish the code -I have to translate the comments from spanish to english, so I will do it only on request