Apparently the fantasticness of Gmail is soon to be available for business use, with Google now piloting the service within San Jose City College in San Jose, California. They're also accepting registrations from other organisations interested in taking part, via the original blog post. (How scary does the 'Google Blog' sound?)
This kind of service that offers a real compelling alternative to the hosted Outlook type of service that we use for email at Alfresco at the moment. With 2GB of storage per user and the power of Google's search technology, this is going to turn the market on it's head.