Comparing different cloud computing services

Came across this link via Mukul's post.
Cloud versus cloud: A guided tour of Amazon, Google, AppNexus, and GoGrid

To test out these services, I spent a few days with them and deployed a few Web sites. I opened up accounts at four providers, configured some virtual servers, and sent Web pages flowing in a few hours. Our choice of four providers wasn't as scientific as possible because there are a number of new services appearing, but I chose some of the big names and a few new services. Now, I can invoke Joni Mitchell and say I've looked at both sides of these services and offer some guidance.

A must read!

In my opinion, some more interesting service providers in this are:

1. Joyent: They have recently partnered with Sun to provide free scalable on-demand infrastructure to Google OpenSocial and Facebook developers. More details here and here.
   
   
2. Slicehost: Probably Slicehost is less about Cloud Computing and more about Xen based VPS hosting. However, multiple slices can be configured for load balancing. They have very good prices and offer a lot of flexibility. They are especially very good for developers who are in the initial stages of launching a web based service.
   

Both are Unix based. Joyent pretty much is a Solaris only shop and Slicehost uses Xen VPS.

It may also be useful to compile a list of sites that experience heaviest traffic and find out:

1. If they manage the hosting themselves by using traditional dedicated hosting.
   
2. If they use one of the cloud computing services.
   
3. If they use a VPS based solution.