Application Virtualization Defined
Application virtualization is a mechanism that decouples the application from the OS layer, much the way server virtualization decouples the OS from the physical hardware. 

Business Benefits of Application Virtualization
Application virtualization reduces infrastructure costs by centralizing IT and helping to minimize downtime. It also decreases the costs associated with managing deployment and desktop management of software packages. In addition, application virtualization helps companies meet business continuity and DR requirements.

Technical Benefits 
Application virtualization offers many technical benefits as well, including easing the pain that IT administrators experience when migrating desktops from XP to Vista and drastically reducing QA and regression testing cycles. It also simplifies change management since application changes do not require a desktop update.

In addition, application virtualization removes DLL and application version conflicts. Plus, no more missed prerequisites or failed installations. And finally, all application files, dependencies, registry keys, etc. are compiled into a single container.

Security Benefits of Application Virtualization
Simply put, application virtualization offers companies a more secure desktop environment. For example, packaged/sequenced applications are not altered even when users change preferences. Plus user profiles/sandboxes can be cleaned up upon closing the application. This ensures a pristine state for every launch.

Who Are the Application Virtualization Players?

VMware—ThinApp
ThinApp is a client-less application virtualization solution that allows any application to be packaged and distributed as a single EXE on a host PC without installation or changes to the local desktop registry or file system. It does not require preinstalled software on the client or the server. ThinStall applications can run from any device such as desktop, LAN, WAN, USB flash, etc. using the existing infrastructure.

ThinStall applications run entirely in user mode on locked down PCs with no device drivers installed enabling administrators to maintain a secure, clean, and stable desktop environment.

Microsoft—SoftGrid
Microsoft SoftGrid application virtualization employs an innovative system for centrally deploying applications. Rather than “pushing” down and installing entire applications, the first time an application is requested by end users, the SoftGrid client rapidly responds and “pulls” only the code necessary to start the program from a central Virtual Application Server—typically 20-40% of the total code depending upon application.

The core of SoftGrid's intelligent management is the SoftGrid Management Web Service which provides a central service for administering SoftGrid servers and applications. Through this, you can publish applications and control server settings.

When the session terminates, the application and its user preferences are saved in a file-based cache location. Subsequent launches are called from this local cache resulting in faster launches with little impact on bandwidth—ensuring that applications are also preserved, even in the case of unexpected computer shutdown.

The Future of Application Virtualization
In the next few years, application virtualization will become more than just a mechanism to overcome software conflicts and lock down the desktop. Application virtualization will also soon become fully integrated with endpoint security strategies, virtual desktops, and ultimately drive the remote office and DR strategies within your organization. Whether companies end up trending more toward Microsoft or VMware’s technologies—or others—there’s no doubt that application virtualization will become an essential component of the corporate desktop.