I like this idea a lot. It is still in the development phase but has great potential. There are several US versions of this idea most notably RecordLinc. However RecordLinc is financed by user fees and the Canadian e-Referral is a service of their dental association that is free to members.
The benefit, that is a secure online referral that allows you to easily transfer complete patient data not just a name and a tooth number is huge. The first hurdle is getting enough dentists to participate to reach a critical mass of users.