During my cyber travels this week I came across this interesting article at Byte & Switch highlighting VMware's new paravirt-ops, a paravirtualization interface for Virtual Workstation 6, and the difficult choice it presents to IT executives in the near future.
Paravirt-ops is basically a means to enable virtual environments without having to recode for hardware-assisted virtualization from Intel or AMD. The problem is, it does this by mucking around with the operating system kernel, which is no big deal for Novell, Red Hat or any of the other Linux crowd. Microsoft, on the other hand, is, shall we say, peeved. Paravirtualization also makes it difficult for application providers to support their own products.
So, on the surface, it would seem there is a simple choice between the paravirtualization approach backed by VMware and XenSource vs. traditional hardware assist from Virtual Iron. Would that it were, as VMware will likely support both methods on various products going forward. So it would be to your benefit to make sure you know exactly how your new virtual environments are being created.