Gladwell makes a distinction between "visionaries" who invent new things and "tweakers" who refine, perfect and make new inventions work. Gladwell proceeds to argue that Jobs falls into the tweaker category.
Gruber keeps talking about "innovations", a word Gladwell does not use, without bothering to explain what he means by it or how it is different from Gladwell's idea of "tweaks." But he has no problems claiming that Jobs "innovations" were not tweaks. He asks: "Does anyone really think Apple’s entry into the music industry was a 'tweak'?" Yes, according to Gladwell's definition of the term it was. It seems that Gruber did not bother to try to understand what Gladwell meant by the term "tweak."