The power of an Amazon EC2 small instance has remained the same for years http://aws.amazon.com/ec2/instance-types
With EC2 there is no steady increase each year in computing power. It's like Moore's law has been frozen in time. EC2 server instances are looking decidedly old and underpowered.
Amazon gets all the benefit of hardware costs decreasing and computing power increasing over time, but no increase in power gets passed through to EC2 users.
Very sad. Slow old cloud computing servers are starting to make running your own powerful modern, cheap, fast servers look attractive.
Will cloud computing vendors start to seriously compete on computing power?
The newer m2 instances use x5550 Nehelem hardware and perform quite well. You'll generally get the most compute power for the money with an m2.xlarge instance (6.5 ECUs) which generally performs much better than the supposedly 20 ECU c1.xlarge Xeon E5410 instance. m2.xlarge can generally be had for around $0.17-0.30/hr (spot pricing) which is very reasonable for 17GB ram (compare to Rackspace Cloud $0.96/hr for 16GB cloud server running on less powerful Opteron 2374 hardware).
If you are interested in other providers, I've done a complete specs/performance/price analysis of 20 different cloud providers including EC2 here: http://blog.cloudharmony.com/2010/05/what-is-ecu-cpu-benchma...