After reading a report yesterday saying that Rackspace cloud servers were a better deal than Amazon's, I decided to check it out today.
I don't have time to do a formal benchmark, so I created a Rackspace-hosted clone of a system that is having trouble keeping up with its workload on EC2. I chose the cheapest option on Rackspace, a 1GB 32-bit Windows 2003 server that costs $0.08 per hour, which works out to $59 per month. Significantly less than the $90 a mini-server costs on Amazon.
The result was shocking. With the same load that pushed EC2 to it limit, CPU-wise, the Rackspace server bareley got off the baseline. So I kept adding more load to the Rackspace server. It's now doing something like 1.5 the work of the EC2 system.