One product, vCenter AppSpeed, is the result of VMware's acquisition of application performance vendor . VMware says that AppSpeed provides service-level reporting and performance management for multi-tier applications that run in VMs, giving "IT administrators visibility across all tiers of an application, providing views of application performance, usage and dependencies, across both physical and virtual infrastructure."

The idea is to increase application performance and uptime and troubleshoot performance problems. While many customers have targeted low-hanging fruit by print and file servers, there is some trepidation about virtualizing business critical applications such as Exchange, CRM and ERP, says Bogomil Balkansky, VMware's vice president of product marketing. That's why performance monitoring is necessary.

"For these types of applications, there is a higher burden of proof on whether it will perform. Is it going to scale, is my application going to be OK if I put it in a virtual machine?" he notes.

AppSpeed measures latency, showing how much delay is contributed from each source, for example Web servers or data base servers.