I believe Google releases these things for free so that people can help them test it out and help them find the right pricing model. I'm not too sure there are

I believe Google releases these things for free so that people can help them test it out and help them find the right pricing model. I'm not too sure there are a lot of people that will immediately base their business model on a service that has not yet announced the pricing. I think Google has been extremely reasonable with App Engine. Also, Lock-in can be relatively avoided if you write your code correctly.