The reason I'm still wary of the cloud is that the abstractions are still too leaky (to borrow Joel Spolsky's turn of phrase). When you start abstracting away core system calls (like fsync), things work great 99.99% of the time. But when that .01% bites you, it bites hard. We don't expect core system calls (like fsync) to fail. And when they fail, the fact that our code is two or three levels levels of abstraction higher means that we often have no way of fixing the issue. The cloud will be at a disadvantage to "real servers" as long as its abstractions are leaky enough to be distinguishable from real hardware.