So what is a Cloud? Its a data center you don't own. Since most users never visited a data center, the analogy isn't vivid. So we'll continue to hear the Mainframe analogy.
Btw it IS much like a Mainframe when you have a static server cluster in the cloud. Thats not Enterprise but its pretty common, maybe more instances of that setup.
I think the point I'm really trying to make is that you can't just load a program into the cloud. The cloud is more like a software based mainframe if anything, but it requires a whole new set of architectures and a different way of thinking--and has radically different economic forces.