I've been wondering about this too, as I currently have 2 FreeNAS machines sat under my desk so am pretty comfortable with my data (which exist on both, and at least one other) unless there is a fire or someone breaks in an manages to take away all my machines.
FreeNAS1 replicates to FreeNAS2 overnight and I was wondering how easy it would be to move FreeNAS2 to a friends house and simply change the destination IP on the Replication Tasks. Would things just carry on replicating without any more changes, other than some port forwarding on my friends network?