Microsoft Domain Services

Apparently Microsoft is now offering domain services. Over at Windows Live Custom Domains I was able to setup email services (MX record) for each of my registered domains. The services generates a unique hotmail mail server subdomain for each domain. I edited my domain services MX record to point to the hotmail mail server and created a new mail user. Voila, I can now login to hotmail with userid@mydomain.com and send/received email. I wonder where Microsoft is going with this?