Because you're a reader of Linux Journal, you probably already know that Linux has a rich virtualization ecosystem. KVM is the de facto standard, and VirtualBox is widely used for desktop virtualization. Veterans should remember Xen (it's still in a good shape, by the way), and there is also VMware (which isn't free but runs on Linux as well).

Virtualization is now a staple of the modern enterprise. As more and more shops switch to the virtual paradigm, managing those new virtual resources is a critical part of any deployment. For admins using Microsoft- or VMware-based hypervisors, powerful management tools are available to keep their virtual houses in order.