Some virtualization vendors say that the application support issue is being overblown. Among them is Parallels, a company that until last week was known as SWsoft. Parallels sells Virtuozzo, which IDC counts as the third most popular x86 virtualization platform behind VMware's and Microsoft's technologies.

Parallels has a back-line support agreement with Microsoft such that if a customer has a problem with a Microsoft application running under Virtuozzo, the software giant is "contractually obligated to help us support them," said Parallels CEO Serguei Beloussov. "Sure, support is a bit of a grey area, but every vendor provides their best effort of support."

Similarly, VMware says that despite Oracle's seeming proclamations to the contrary, customers running Oracle apps on ESX Server will still have a support safety net to rely on.

Next June, Microsoft plans to start a testing program that is designed to enable users running validated virtualization platforms from other vendors on Windows servers to get technical support on a cooperative basis from either Microsoft or the virtualization provider.

For its part, VMware is making "special investments" with ISVs to encourage certification, according to Patel. For instance, it opened a small support office at SAP's headquarters in Germany to help the business applications vendor with certification and support issues.

Companies like SAP "are giving us the solid green light" on application support, Patel said. "Companies like Oracle are giving us more of a yellow light. As the months progress, I think Oracle will become more of a minority."