The key word for today is virtualization. And verily, it is virtually good.

Less than six months after acquiring Thinstall in January, VMware has announced, at Microsoft Tech-Ed Professional being held in Florida today through Friday, that it's releasing VMware ThinApp 4.0, based on Thinstall's product.

This has two new features, Application Link and Application Sync. These enable two virtualized applications to communicate with one another, and let systems administrators update virtual apps remotely.

"We decouple operating systems from the hardware by virtualizing key resources like networking, the CPU, memory and disk, and allow the OS to be contained in a VM, and let multiple VMs run on the same server or on different servers, fully encapsulated from the hardware," VMware's Ed Albanese told me, adding that the company's approach to application virtualization is "very innovative".

This approach eliminates system conflicts so you can "deploy an XP or Windows 2000 image in a Vista image and move the VM from one PC to another at the desktop," Albanese told me, adding that the image can be deployed anywhere -- "a terminal services environment, a Citrix environment, a physical PC, a virtual desktop, a USB key stick." OSes supported are Windows XP, NT, 2000 and Vista; and the application supports 32- and 64-bit Windows hosts.

Fascinating...but being able to bung your VM onto a thumb drive et cetera are pretty standard when you use virtual images. And it wasn't a million years ago that I wrote about Xenocode, which virtualizes applications and lets you "run Office 2003 and 2007 side by side on the same desktop or run IE6 on Windows Vista" and about MokaFive's Virtual Desktop Solution, which automates lifecycle management for virtual machines.

Xenocode uses its own hypervisor while MokaFive uses VMware's VMM (Virtual Machine Monitor) -- the core virtual layer that separates the hardware from the software -- and builds intelligent services around it.