Over the past month, I received a couple of tips claiming that Apple was a Windows Azure customer.

At first, I just dismissed the tips as nothing but a crazy rumor. Then I got more serious and started asking around, to no avail.

But once Apple launched the beta of its iCloud iMessage service, the Infinite Apple site, along with a few other blogs, analyzed the traffic patterns and found that Apple appeared to be using both Azure and Amazon Web Services for hosting.

"We don’t believe iCloud stores actual content. Rather, it simply manages links to uploaded content," according to an updated June 13 Infinite Apple post.

I asked Microsoft for comment and was told the company does not share the names of its customers. I asked Apple for comment and heard nothing back.

I've heard some speculate that Apple may simply be using Azure's Content Delivery Network (CDN) capability. The Azure CDN extends the storage piece of the Windows Azure cloud operating system, allowing developers to deliver high-bandwidth content more quickly and efficiently by placing delivery points closer to users.

Based on Infinite Apple's info, Apple seems to be using Azure's BLOB (binary large object) storage, which is part of the Windows Azure core. However, the Windows Azure Content Delivery Network (CDN) is integrated directly with Azure's storage services.

Apple's iCloud is still in beta, and Apple is just in the process of turning on its much-touted $500 million North Carolina data center. Apple's datacenter, as my ZDNet colleague Larry Dignan noted, is running a combination of Mac OS X, IBM/AIX, Sun/Solaris, and Linux systems.

Maybe Apple's seeming reliance on Azure and AWS -- in whatever capacity they're actually being used -- is temporary. It's still interesting, though. (And probably something the Softies wish they could use in an official case study.)