I'm running a Pollin-NetIO (http://www.pollin.de/shop/dt/MTQ5OTgxOTk-/Bausaetze/Diverse/Bausatz_AVR_NET_IO.html), a real cheap ATMega32/Ethernetboard with an ATMega644 as Arduino/Sanguino-clone. There is an AddOn available that has RFM12 support.
I finally got the RFM12 running after hours of code-watching. The library defines RFM_IRQ as the pin that connects to the nirq of the RFM12 (line 15 of RF12.cpp), but the attachInterrupt call on line 213 uses a fixed value 0.
I thought there is a function to get the interrupt for a pin, but i can not find it. If there is none, maybe RFM_IRQ could be renamed to RFM_IRQ_PIN and RFM_IRQ could be used for the interrupt number.
Thanks for sharing all that stuff! After resolving the problem, everything work great!