The difference with the Sokal Hoax is that it cuts to the core of what philosophers do: Whereas science has practical, tangible results to show, such as the polio vaccine, all philosophy has is thoughts and ideas, which the Sokal Hoax assaults very directly.
Philosophy most certainly does have tangible results to show, for instance: modern democracy, the scientific establishment itself, the various international bodies that enforce civil rights, and the modern field of psychology. If you go far enough back, philosophy gave birth to all intellectual forms of knowledge, which in turn greatly influence all aspects of our society.
This got me thinking: what tangible results have arisen from current philosophy, that is, philosophy we've seen in the last, say, 20 years?
> philosophy gave birth to all intellectual forms of knowledge
I think this is an utterly unsupportable claim unless you're willing to simply define philosophy as encompassing all other forms of intellectual pursuit. Intellectual knowledge (whatever that means) existed long before the Rig Veda and Socrates.
An easy example is modern activist tactics, i.e. Seattle and Occupy Wall Street. Another hackneyed example is Israeli military tactics, which have been said to have been influenced by writings of Gilles Deleuze.
Above and beyond specific examples, it's important to note that world affairs are influenced considerably by people in positions of power. Such people tend to be well educated, which often means they've been exposed to and influenced by contemporary philosophy. For instance there is a large body of work on international politics. I don't think it's too much to assume that policy-makers at that level have some knowledge of current discourse in the field. For instance the debate about whether a world government would be a good thing.
It depends on what you mean by tangible. You're meaning here seems to be something like "having a direct impact on the physical sciences", a very limited question considering the breadth of the topics covered by philosophy but certainly the answer even in this limited context is more than zero tangible results. Much research in artificial intelligence and machine learning is directly inspired by philosophy and has been since the beginning, so that would be a great area to start in. There has also been much work in the philosophy of language, science, mathematics, ontology and other branches of metaphysics, politics, aesthetics if you're willing to broaden your criteria for tangibility.
I'm defining philosophy very broadly as written, systematic knowledge in the West. All major branches of knowledge where once subsumed by the title "philosophy". For instance, what we know of as science was previously called "natural philosophy". What we now know as "political theory" was once indistinguishable from "philosophy". And political science is a combination of the latter forms of the two. It began with this: http://en.wikipedia.org/wiki/Trivium_(education)
Meh. By that definition, what we now know know as philosophy is not what used to be philosophy. By the same tack, I could define "hot dogs" as all written, systematic knowledge in the West, and thus claim that hot dogs predated all intellectual pursuits.
Seeking tangible results shouldn't be the goal of philosophy. Philosophy is not about tangible results. At its core, it's about thinking clearly.
It's my opinion that if scientists today had a better grasp of philosophy, then the string theorists and researchers studying dark matter would have come up with tangible results already, either by changing their models to actually make predictions, or dumping their models altogether and study alternatives. They would have tangible results instead of always being surprised that we can't find dark matter or surprised that new particles weren't produced at a given collider. Instead of demanding that larger and larger colliders be built, they would reflect on the models they have and attack the weaknesses. Instead of making increasingly sensitive instruments to find interactions between detectors and dark matter that might not even be there, they would give more serious considerations to alternate theories of gravity.
