Web hosting? So 1990s. Rackspace is now into "cloud computing." The company has acquired Slicehost, a small but popular virtual private server host, and JungleDisk, an online-storage startup. The deals comes as Rackspace is pushing its Mosso service as an alternative to Amazon.com's computing-power rental offerings. The question is now this, will Rackspace bring their world-class downtime to both services?