It doesn't preclude it, but SOAP routing gets more interesting when you take HTTP out of the picture and look at other transports..
Being a courious mind and all that, I ask: What other transports? I'd seriously like to to know just what protocols are being considered as replacements for HTTP in these scenarios (I'm not an big fan of HTTP, mind you, altough it does serve its purpose). So, Simon, care to enlighten us? ;)