I've looked pretty closely at EC2 and ended up deciding against it. With any of these services (EC2, AppEngine) you're basically building your system on one big

I've looked pretty closely at EC2 and ended up deciding against it. With any of these services (EC2, AppEngine) you're basically building your system on one big fat single point of failure. I would rather build up an assortment of disk images pre-configured for the needs of my system's components and then deploy them as needed onto a system that supports them (eg. Slicehost).