This 'cloudbursting' is what a lot of people, ourselves included, are doing. Basically we run 2 servers for one of our projects and these serve up content, prov

This 'cloudbursting' is what a lot of people, ourselves included, are doing. Basically we run 2 servers for one of our projects and these serve up content, provide 'my account' services and a sales function. We use AWS for the heavy lifting and we run up to 100 instances at a time for processing. We decided not to go 100% AWS because whilst we trust them to a degree, there have been some outages and having a hybrid approach means its easier to communicate with our customers and to provide some kind of buffer if there is a problem with AWS. The bottom line for us is that we are able to do stuff now that would have been prohibitively expensive before.