(September 9, 2008) - Microsoft’s cannon started pounding away on Tuesday at the walls of the market fortress that VMware, the established leader of server virtualization, has built.

They went off earlier than they were supposed to by a day when Forbes tripped over an embargo, releasing all and sundry in the press from their collective timing promises.

It will take months for this week’s fusillade, the results of Microsoft’s Virtualization Deployment Summit in Redmond, to clear enough to see if any of the mortars scored a direct hit because Microsoft’s repeatedly delayed retort to VMware, the free, catch-up, first-generation Widows Server 2008 hypervisor widgetry called Hyper-V still won’t be out until at least August, according to Microsoft, six months after the also delayed Windows Server 2008 is finally released in February.

In the meantime, Microsoft’s assault is sure to send shudders through VMware’s $31 billion market cap – already down 35% from its October high on concerns over possible competition – if for no other reason than the market is so darn skittish these days.

The ammunition Microsoft is using against VMware includes an acquisition of a California desktop virtualization start-up called Calista Technologies Inc.; an expanded alliance with Citrix that co-ops XenSource, the open source rival of VMware that Citrix recently bought even more than it already was; price cuts for large accounts running Windows in virtual machines; and the reversal of a policy banning consumer versions of the Vista operating systems, Home Basic and Home Premium, from being virtualized.