VMware Inc. reacted quickly to Red Hat's integrated virtualization roadmap this week, which uses open source Xen instead of VMware. Meanwhile, Red Hat Inc. chief technology officer Brian Stevens said VMware is still a key partner, while other virtualization players refused to choose sides.

Virtualization market leader VMware takes the stance that efficient virtualization can only be achieved with operating system independence, while others -- like San Francisco-based Linux clustering vendor Penguin Computing Inc. -- took a more optimistic wait-and-see approach.

"If you want to partition a server or run a legacy operating system, the functionality may reside anywhere. Enterprise virtualization, on the other hand, is about deploying virtualization as a core IT strategy for OS/application provisioning, sever consolidation, mobility, disaster recovery and systems management across all OSes, applications and hardware," said VMware vice president of data center and desktop platform products Raghu Raghuram.