Hi Jeff,
yeah, I did it for sms.capesoft.com
It's not terribly exciting - Twilio calls your web hook, which is jsut a NetWebServieMethod, and you can then process that like any other method.
I went a step further - the sms.capesoft.com server then has WebSockets connections from the clients. So if a client program sends an SMS, and that SMS gets a reply, then it's automatically pushed back into the client program, in real-time, even if the client program is behind a firewall.
If you're not too worried about doing it yourself, I can hook you up with a beta account on sms.capesoft.com to play with.
cheers
Bruce