I played yesterday in the Nationwide LaSalle Bank Open Pro Am and was paired with Jason Gore who is a Nike guy. He plays a tour Ignite with the same steel shaft Tiger uses. He did not say what the name of the shaft was, only described it as a prototype. The way he described is was "take a typical X-100 and remove a 6-8" piece of the shaft above the tip (approx. 4 inches from the tip) and replace it with a lighter weight steel" Effectively, creating all the benfits of an X-100 but a slightly lighter weight. Not sure any other details but he can definately pound it.
On another note, he had the sweetest set of "JG" stamped, custom ground raw Nike split cavities and an unmarked tour nike slingshot 2 iron that has a much narrower sole and a little thinner top line. He referred to it as "money" and hit it off a lot of tees.
Hope this helps.