Of course, no market segment is complete without an interloper to shake things up. Thinstall combines the simplicity of SVS with the fully padded box approach of SoftGrid. By embedding both the virtualized environment and the application image into a single executable file, Thinstall eliminates the need for supporting infrastructure: Just copy or stream the file to the client and execute. No agent is required and the image can be deployed using virtually any traditional management suite, including Active Directory and Microsoft Systems Management Server. The downside is the need to customize the application using Thinstall's Virtualization Suite toolset.

Classic virtual machines

In some client situations, a more comprehensive virtualization solution is required, such as hosting a legacy application on a new operating system. In that case, it may be best to isolate an application within a complete, virtualized OS environment -- the classic "virtual machine" approach. This enables you to run an application within the OS image of your choice while still supporting migration to, and integration with, newer or otherwise incompatible OS platforms.

VMware and Microsoft dominate the classic VM market, with VMware the more visible of the two. Efforts like the VDI (Virtual Desktop Initiative), a consortium of vendors promoting virtualization as a desktop and application management solution, are being driven primarily by VMware.

VMware has also been quick to embrace new CPU and hardware technologies, such as 64-bit processing and expanded memory for next-generation applications. VMware exclusives, such as the ability to take snapshots of a VM's running state and "roll back" to a saved image have earned affection from the developer community. But in the end, VMware's willingness to expose its underlying virtualization technology to the masses may pay the biggest dividends.