i'm curious as to how the black market on something like this would work. my knowledge is limited on the chips themselves, but they seem like something that would likely only be purchased by companies serving a high volume of traffic (thereby making the chips hard to sell on the black market because of the reluctance of large companies to deal with second hand goods of questionable origin).
The market for Cisco equipment is large and diverse (not just Web 2.0s but ISPs, enterprises, universities, etc.), there are plenty of vendors of used Cisco equipment, and given the economic collapse more people are buying used equipment. In particular, the Cisco 6500 is a very popular family of switches.
Cisco frowns upon purchasing second hand equipment from "unlicensed" vendors. They claim that their software is non-transferable meaning that you technically don't own any of the IOS that comes with used routers. So if you need an upgrade or security update you are basically screwed until you fork over a ton of money.
The most valuable cards are the supervisor modules, which are the ones which actually run the IOS. But I wouldn't be surprised if the Cisco licensing agreements apply to all their cards.
All the cards have some pretty clever distributed forwarding smartness in them.
I've never heard of IOS having anything to do with Linux. Cisco owns Linksys now, and most (all?) Linksys routers are based on Linux, but that's no secret.
Cisco branded products run some form of IOS, and IOS has always been Cisco secret sauce. A few years ago, some IOS source code was stolen and parts were made public. I think if any of it contained Linux kernel code the Internet would have erupted into fury.
On a somewhat related point, Juniper JunOS is based on a BSD variant (FreeBSD I think), but there is no way to know how much is BSD and how much was developed by Juniper. It's a consequence of the BSD license.
