
Rackspace is well-positioned to stay ahead of new cloud competition, given its value pricing and reputation for customer service.
--Goldman Sachs Research Dept.
Rackspace has been in the mainstream hosting business for over a decade, and was amongst early entrants into the utility computing market with the launch of Mosso back in 2006. They are listed as a leader in the upper right of Gartner's December 2010 Cloud Provider Magic Quadrant, available for free on competitor Savvis' website.

Rackspace offers public and private cloud solutions.
As of October 2009 for their public cloud, RackspaceCloud is running a close second to Amazon AWS with 1558 of the top 500k websites as clients according to Guy Rosen's Jack of All Clouds blog. RackspaceCloud is growing faster with 10% growth from Sept-Oct vs Amazon's 4.5%. There are contractual differences between the offerings of Amazon and RackspaceCloud. Here's a detailed comparison of Amazon's SLAs with RackspaceCloud.
Rackspace's private cloud managed hosting service was launched in July 2009. It allows customers to run the centrally managed VMware virtualization platform on private dedicated hardware environments.
In addition to their own cloud computing services, Rackspace offers Database-as-a-Service (DaaS) from FathomDB, to enable businesses and developers to easily manage their MySQL databases in the cloud. FathomDB offers a range of time-saving features, including automated backups and routine maintenance tasks, powerful analytic tools, real-time monitoring and performance graphs for optimizing code, and easy point-and-click configuration.
Rackspace's 2009 Q2 statement lists their number of cloud customers growing from 35K at the end of 2008 to 43K at the end of Q1 to 51K by the end of Q2, 2009, confirming excellent growth. Cloud revenue has risen from $9MM to $11MM to $13MM over the same period, putting them on pace for over $50MM in cloud revenue for 2009. Rackspace's total 2009 annual revenue will be around $600MM. Their balance sheet appears sound almost a 2-1 asset to liability ratio. Assets are increasing and liabilities decreasing. They do not have expensive convertible debt such as competitor Terremark.
Rackspace provides the thoughtful cloud marketing site NoMoreServers.com with a great rebuttal to the McKinsey anti-cloud computing report.