Emulation vs Virtualization technology

"... while emulation essentially creates an entire hardware environment that may bear no relation to the actual hardware of the machine it's running on, virtualization provides an indirect access layer to the actual hardware of the host system." -- Tom Haddon, Linux.com

QEMU

For emulation in the Linux OS, one can turn to many solutions, but one that came to my notice recently is QEMU, via this article, which is capable of x86 and x86_64 32 and 64 bit user code, supporting the following OS's: GNU/Linux, Windows 9X, 2000, XP, Solaris 9/10, NetBSD, and so on...

XEN

For emulation pure virtualization, the Xen project is the leading open source virtual machine, and RedHat has shown recent insterest in putting effort to include support directly into the kernel.
In my own opinion, and based on recent articles and fuss-fuss not only on the net but in the IT buiseness circles, virtualization is going to be the next BIG thing in IT: having hit the frequency barrier, and with CPU companies pushing the multiple core solutions, this will drive the software to follow two main streams:

• on the side of the software applications, more and more will be multi-threaded, to explore the full potential of the multi-core architectures.
• on the side of the operating systems, they should start to support virtualization at the lowest (kernel) level, to allow for multiple machines to be emulated, yet centralized, thus simplifying maintenance and improving uptime.