I'm fine with interoperability. Viewing it logically, people looking for interop will find interoperability and will know what it is. People who are not sure what they want may be confused by interop.
@JM I vote for interoperability, but we can make interfacing a synonym. I think interoperability is better because it is more general. It is also appropriate for e.g. data exchange formats (how can I transfer a sparse matrix from Mma to MATLAB? <-- this was a real question of mine)