In a move that should make it less costly for IT shops to implement virtualized architectures, Microsoft said Tuesday that it is dropping the additional license fees it charges customers when they move server software from one host computer to another.

"Businesses are taking steps to make their IT operations more dynamic and are delving into virtualization as a cornerstone strategy," said Zane Adam, Microsoft's senior director for integrated virtualization, in a statement.

"Microsoft recognizes this and is innovating its licensing policies, product support, and a wide range of IT solutions to help customers get virtual now," he added.

The fee-elimination program applies to 41 Microsoft server applications, including certain editions of SQL Server 2008, Exchange Server 2007, Dynamics CRM 4.0, SharePoint Server 2007, and Microsoft's System Center products. InformationWeek has a more in-depth analysis of these products. Download the report here (registration required).

Under the new rules, IT managers will be allowed to port the applications back and forth between host servers as often as they want, without incurring additional costs. The program takes effect Sept. 1.

Microsoft previously tied server licenses to the physical hardware on which the software resided, which limited users' flexibility. In modifying its license terms, Microsoft appears to be bowing to users' desire to create virtualized infrastructures, in which a server application may be tied to numerous boxes or can live side by side with other server applications within a single box.

Virtualized servers allow users to devote more hardware to an application during peak usage times and can also help save space and energy in the data center. IDC research VP Al Gillen said virtualization "is quickly becoming a mainstream solution" in enterprise IT environments.

Microsoft itself is promoting virtualization through its Hyper-V hypervisor product, which is part of Windows Server 2008. A hypervisor coordinates activity between server software and hardware in virtualized environments.

Microsoft also said it's expanding its technical support program for server software to cover topics related to virtualization. "Now customers can get the same level of product support in a virtualized environment that they are accustomed to with nonvirtual environments," Microsoft said.