Finally Microsoft has stepped out of that box and signed an inter operability agreement with Red Hat that excludes any mention of patents. The agreement is aimed at improving inter-operability between the two companies' virtualisation products. The companies will join each other's certification and validation programmes as well as provide technical support for mutual customers, as part of the agreement.

In terms of the agreement, Microsoft will validate Red Hat Enterprise Linux 5.2 and 5.3 guests on Windows Server 2008 Hyper- V and Microsoft Hyper- V Server 2008 while Red Hat will do the same for Windows Server 2003 SP2, Windows 2000 Server SP4, and Windows Server 2008 guests on its Red Hat Enterprise virtualisation technologies.

It is expected that the customers will be in a position to receive "cooperative technical support for running Windows Server operating system virtualised on Red Hat Enterprise virtualisation, and running Red Hat Enterprise Linux virtualised on Windows Server 2008 Hyperv." It may also free up users to investigate both options in a non¬exclusionary way. And for Microsoft it is yet another sign that the company is opening up to the open source community and is changing the way it behaves. However this agreement is very different to ovell's patent backed inter-operability agreement with Microsoft back in November 2006. That deal put Novell at odds with open source advocates critical of patent deals.