The problem with cloud computing from a business model perspective is that most companies that get to the point of using that many resources, can also afford the hardware and bandwidth to make it work in house.
This is also true of services like EC2 and Cloudera.com which aim to offer Map/Reduce and raw distributed computing in the cloud on demand to businesses.
Most bandwidth providers provide burstable bandwidth, and most companies have to use virtualization to even get close to the maximum use of resources on the machines they do have, much less outsource that on a rental basis with metering.
To try to rent it to them is patronizing them on a grand scale, so we'll see if the marketing can overcome the actual demand.
App Engine and GWT have been around for a while to the tune of an only limited success. I understand that MS has their platform exclusivity, but I don't think that will make it more attractive at all.
There are some *really* smart people out there that are doing next gen cloud platforms, but they have not yet emerged. We will have to keep an eye out for developments on this front.