If your entire data center infrastructure is on one virtualized PC, you're doing it wrong.
Where's F5

The comparison between the power of a modern PC and a 1960's mainframe is often made in conjunction with a smug "look how far we've come" look.

But the way virtualization is headed today it's likely that mainframe holdouts will turn that smug look back on us with a blithe, "yes, you've gone all the way back to beginning."

If we're not careful, by the time we're through deploying virtual everything we're going to end up with a single PC comprising our data center. Which is pretty much like a mainframe, isn't it?

We're certainly headed that way. Virtual appliances for security, for switching, for many functions handled by network infrastructure are arriving daily. And we're lapping them up like a cat given cream.

Now I'm not going to go as far as @Beaker in his Four Horsemen of the Virtualization Apocalypse and claim that every time you deploy a piece of network infrastructure as a virtual device that God kills a kitten; but I think He just might kick one every time you deploy what is traditionally a network infrastructure function within a virtual appliance.

L2-3 switching used to be done in software, before the advent of network processors and high-speed backplanes and switching fabrics. When there were no VLANs (Virtual Local Area Network) and there were no ACLs (Access Control List) and there was nothing but forwarding of packets.

Routing used to be done in software before there were route optimizations and link load balancing and complex algorithmic configurations designed to optimize the flow of traffic in and out of a private network.