Razorfish, one of the largest digital marketing companies in the world and an independent Microsoft subsidiary acquired when Redmond bought aQuantive, is going to use Rackspace Hosting's Mosso cloud hosting platform.

What it's not doing, of course, is waiting around to use Windows Azure, Microsoft's nascent cloud, which may get off the ground by the end of the year.

It will use Mosso's Microsoft infrastructure and perhaps cut its internal infrastructure costs.

Razorfish says it'll use Mosso for consumer-facing web sites and web applications that can handle large spikes in traffic during major promotions and product launches. Mosso scales.

Razorfish also uses Rackspace's managed hosting widgetry and has developed microsites, community platforms, blogs and web video for its clients using Mosso's Cloud Sites and Cloud Files hosting services.

Razorfish, formerly called Avenue A Razorfish, counsels clients on how to leverage digital channels such as the web, mobile devices, in-store technologies and other emerging media. It says it's increasingly advising marketers on so-called social influence marketing, its approach for employing social media and social influencers. Its clients include Carnival Cruise Lines, MillerCoors, Levi's and McDonald's.