They have officially announced a beta program that describes almost exacly what I mentioned in my previous post about GMail for domains. You can read more about this service here.
They are already providing this service to San Jose City College, and have extended the beta program to any companies who wish to take part by filling in the request form.
Update: It even looks as though Google might be flexible when it comes to customizing the look of your hosted GMail solution. Visit the San Jose City College login screen and you will see that they have their own custom logo.
For people who are interested in the MX records used for the San Jose City College, you can find them here.