Microsoft is continuing to move more of its biggest cloud services onto its Windows Azure public cloud.

According to a December 16 post by The Register, which quotes Corporate Vice President Scott Guthrie, Microsoft already has moved its Skype service onto Windows Azure.

Back in 2012, Microsoft execs confirmed they were moving part of the Skype infrastructure to Microsoft-hosted supernodes in Microsoft datacenters. Officials wouldn't comment at that time when I asked about the operating system/environment on which they were hosted.

In September of this year, Microsoft execs said there were 50 billion minutes of Skype-to-Skype calls running on the Windows Azure cloud. But, again, they never said which parts of Skype's updated infrastructure were actually running on Windows Azure vs. on other platforms.

Guthrie also said in the new Register interview that Microsoft's SkyDrive cloud storage team is "in the process of decommissioning their old servers and moving everything onto Azure."

"All new storage on SkyDrive now goes to Azure," Guthrie told The Reg.

Guthrie moved from the Developer division to the Windows Azure team back in 2011.

Microsoft execs have said publicly that Microsoft is building most, if not all, of its new cloud services and features to run on Windows Azure from the get-go. But Microsoft isn't planing to move all of its legacy cloud services -- such as Hotmail/Outlook, Xbox Live and Bing -- to Windows Azure. Instead, at least for the forseeable future, they'd continue to run in Microsoft's datacenters on their own dedicated servers, I was told.

(And before I hear from anyone with quibbles about Xbox Live and Azure, when I asked this fall, I was told only "portions" of Xbox Live and various Xbox games – including all of Halo 4’s online services - run on Windows Azure.)

Microsoft execs committed several years ago to moving Office 365 to run on Windows Azure. While the Office 365 team integrates with Azure features, such as Windows Azure Active Directory (WAAD), Office 365 still doesn't run on Windows Azure, nor do its component parts -- SharePoint Online, Exchange Online or Lync Online. Microsoft CRM Online also uses WAAD, but as far as I know, is not hosted on Windows Azure.

I asked Microsoft execs for confirmation that Skype is hosted on Windows Azure and that the still-to-be-renamed SkyDrive is up next. No word back so far.