Mary Jo Foley reports that Microsoft will support the ability to create persistent virtual machines on Azure this year. This means that uses will be able to create virtual Linux servers on Azure without losing state. Azure currently has the ability to run VMs, but any time the the server is rebooted it loses state.

A technology preview of this capability is expected this spring.

“The new persistent VM support also will allow customers to run SQL Server or SharePoint Server in VMs, as well,” Foley writes. “And it will enable customers to more easily move existing apps to the Azure platform.”

This move gives Azure a general purpose infrastructure-as-a-service capabilities to compliment the existing platform-as-a-service offering. According to Foley’s sources, the ability to run persistant machines and Linux support are both frequently demanding by customers. But Microsoft apparently won’t officially support Linux and will encourage customers to upload their own images instead.

Microsoft has been gradually warming up the open source community, having open sourced a number of projects and libraries, mostly relating to ASP.NET. The company is also helping port Node.js to Windows and open sourced a JavaScript library for Apache Hadoop.

The company has come a long way since the days of Steve Ballmer calling Linux a “cancer,” but it’s important not to read too much into Microsoft allowing Linux machines to run on Azure. None the less, the move highlights a couple major trends: Microsoft advancing its cloud and virtualization tools to include rival platforms, and the trend for cloud service providers to offer both IaaS and PaaS services.

Update: Foley has posted a 2012 roadmap for Azure.