We're using FreeBSD jails, actually - and AwesomeProxy contains a custom implementation of the MySQL binary protocol. I tried MySQL proxy but it didn't cut it - as it doesn't allow you to fake MySQL authentication and proxy to a different server based on database/username.

Would you like to try it? You can spin it up on EC2 with just your API keys... sign up for the trial at http://www.hybridcluster.com/product/trial and I'll let you in!