There's a bit more info here: https://github.com/redox-os/redox/wiki/URL
The only odd part is that the modules (drivers) themselves are not referenced by URL, but only by a simple word (in the example "port_io").
Also, I wonder how we could combine drivers. For example, (theoretically) instead of using "https" as driver, we could compose it as "HTTP over TLS over TCP", and change any of those subcomponents as desired. With URLs this might become clumsy.
But you could propose doing: tcp+tls+http://www.some.url/?options=here
if you were okay with that. The problem creeps in when that tls fragment needs options and a path of it's own.