Over the past year, I've watched closely as Microsoft's two flagship cloud platforms -- Office 365 and Windows Azure -- gained anecdotal momentum. Each week, I hear from more channel partners and ISVs (independent software vendors) that are embracing Office 365 and Windows Azure, respectively.

But here's the challenge from Microsoft and its channel partners: It seems like the cloud computing world has increasingly gone open source. The examples:

  • The OpenStack Foundation launched last week with the backing of Dell, IBM, Hewlett-Packard and other giants that have vowed to fund the open source cloud computing organization. Much of the OpenStack industry will gather this week at a major conference in San Francisco.

  • Citrix Systems is working with Apache to open source CloudStack. Plus, CloudStack apparently will be interoperable with Amazon's cloud APIs.

  • Eucalyptus, another open source cloud platform, has also vowed to maintain API compatibility with Amazon Web Services.

  • VMware's Cloud Foundry (platform as a service) also has an open source project to which developers and contribute.

Yes, Microsoft recently created an open source subsidiary. And Windows Azure supports a range of open source development tools, with Apache Hadoop for Azure a work in progress. But I keep wondering if Microsoft can keep pace as numerous IT giants -- again, Dell, HP and IBM in particular -- continue to line up behind major cloud open source initiatives.

For smaller channel partners, I still see plenty of potential upside in the Windows Azure world. I believe ISVs such as CA Technologies (ARCserve), Symantec (Backup Exec) and others have been launching their apps in the Azure cloud.

Still, I hear 10 times the chatter around open source clouds. I wonder if all that open source discussion is hype -- or reality.