Erik Carlin wrote a great post on the Mosso blog comparing the cloud storage offerings from Rackspace (Cloud Files) and Amazon (S3). Here's a quick excerpt:
The cloud is advantageous for many reasons and both Rackspace/Mosso and Amazon offer cloud storage solutions. We are frequently asked to compare Cloud Files enabled with Limelight's CDN with S3 and CloudFront. Many of the questions we are asked revolve around cost and performance (particularly CDN). These are very quantifiable metrics so I thought I'd share with you the results of some comparative analysis we've done.
Read the entire post here: A Quantitative Comparison of Rackspace and Amazon Cloud Storage Solutions