"Understand what people are religious about," Suit says, whether it's VMware, Microsoft or even storage.

Storage is becoming more of a hot-button issue for IT departments as vendors encourage customers to let storage products carry more of the responsibility for VM cloning and VM migration tasks.

4. Plan for peer-to-peer workload migrations across multiple infrastructure vendors.

You will need to "promote" and "demote" virtual machines created using different vendors' technologies, Suit points out. In other words, you will need to move VMs around based on whether they need to make use of more expensive, high-availability physical server resources, for example.

Another example: Microsoft's virtualization-related disaster recovery capabilities (at least for now) are not as strong as VMware's, so you may be creating some VMs in Microsoft Hyper-V then moving them to VMware.

5. Prepare to keep close tabs on configuration drift between dependent peers.

If you are distributing VMs across VMware, Microsoft and Citrix platforms, you need to understand how VMs that are dependent on each other are affected in a heterogeneous environment, Suit says. "You want to keep close tabs on the VMs so they stay in sync," he says. One VM can affect another's performance and security.

When configurations between VMs vary, you can get into situations where developers have access to too much data, breaking security best practices. "This is happening a lot," Suit says.

6. Manage your VM lineage.

Where did a particular VM come from? That question can get even trickier to answer in a mixed vendor environment. Consider a master template on VMware that has clones of itself on Xen and Hyper-V, Suit advises. As you patch software and make other changes to the master VM, keep your templates updated.

Why is VM lineage important? In a regulated industry such as financial services, a clone of a VM may have a compliance profile to which it needs to adhere. In a mixed vendor environment, the differing hypervisors can affect that compliance profile, Suit says. For instance, ports and API settings can change a compliance profile. "VMware is trying to address this with Tripwire," Suit adds. (VMware recently acquired Tripwire; the two have already teamed up on a free configuration checker tool.)

7. Take advantage of the OVF specification to standardize VMs.

"It will be very convenient with Open Virtualization Format (OVF) to move the VMs," Suit says. Open virtualization format, an open industry specification in development now, is designed to support movement of a VM between platforms.