And much
reverse engineering of silicon requires access to the silicon. This means eating off the
plastic housing with acid. Very impressive things can be done, and I would wager that if
you passed a sufficiently interesting chip to a guy like Bunnie Huang he'd see about
reverse engineering it.
There are indeed firms that can reverse engineer chips - even dead
ones. One is Taeus International in Colorado. These guys mostly do
work for clients looking for stolen technology.
http://www.forbes.com/forbes/2005/0328/068.html