New analysis of infrastructure-as-a-service providers shows that Amazon Web Services is used for Web hosting by 20 times more sites than Google App Engine. AWS usage for site hosting grew 9% in just one month this summer, the equivalent of a 181% annual growth rate.The analysis was done by Guy Rosen, founder of a stealth-mode cloud startup called InfiBase, which used proprietary scanning tools to analyze the top 500,000 Web sites indexed by Quantcast. InfiBase was looking for usage data on five cloud services: Amazon EC2, GoGrid, Google App Engine, Joyent, and Rackspace's Slicehost.

Amazon EC2 ranked highest, in use by 1,550 of the half-million site analyzed, followed by Rackspace Cloud Servers (1,373 sites), Joyent (205 sites), Google App Engine (78 sites), and GoGrid (42 sites). Parsing the data, InfiBase determined that the number of Web sites hosted on Amazon EC2 grew 9% from July to August. It also found that 178 sites were new to EC2 in the past month, while 50 sites dropped EC2, indicating a churn rate roughly of one lost customer for every three that Amazon signs.

Rosen took a little flak for including Google App Engine in his analysis, since App Engine is really a service for building Web apps with Python and Java than an infrastructure as a service along the lines of EC2, where users can order servers and choose from hundreds of virtualized software instances. Rosen admits that it's an apples-to-oranges comparison, but says he did so because he was curious. (In InformationWeek's ongoing Anatomy of the Cloud editorial series, we will be publishing reports on both the IaaS and platform-as-a-service markets over the next few months.

Notably -- and this may be the most important finding of Rosen's analysis -- the saturation rate of cloud services among the 500,000 Web sites analyzed is still tiny. Amazon may be the leader in the IaaS category, but EC2 is used by less than 1% (.31%, to be exact) of sites studied. It shows that the cloud services market is still in the very early stages of adoption.