host <-> guest port mapping

[humba]

So far, qemu is the only virtualization solution I know off that can handle this - I'd like to map port X on the host to port Y on the guest, irrespective of NAT/PAT and general network connectivity between host and guest (so it should work even in case the VM has no network at all or when the network is disabled/firewalled - so like the folder mapping feature). I guess named pipes (on both end.. not the pipe <-> serial you can find in VB and VMWare) would already be a fair step into the direction (I'm looking at running RPC style communication between host and guest without requiring direct network connectivity).