Is NServiceBus compatible with Mono? Are you / have you run NServiceBus on Mono? If so what issues did you run into?
NServiceBus leverage's MSMQ by default. I know this can be swapped out for different transport technologies, so I would imagine an initial task may involve implementing a provided "IMessageQueue " interface (or something along those lines) from the NServiceBus library that leverage's a cross platform or Unix Specific message queue / transport technology.
Related Question: "How to swap out MSMQ in NServiceBus 2.0 for a different transport technology"