Also keep in mind, whatever URI is designed, it really NEEDS to contain a public key hash in it or some other way of verifying the recipient. Sending to a random IP address, even if secured with SSL, can result in sending to the wrong person. Even if it's something like bitcoin://keyhash:IPaddress/?message=... you need to know that the correct person is at the other end of that encrypted communications like. This assumes that the Bitcoin send-to-IP will be encrypted.