Assuming this isn't a hoax, and the proof holds up, this is front-page news kind of big deal.
As I recall, this has way more real-world practical usage than the Fermats Last Theorem proof.
Read the "Consequences of Proof" section in the Wikipedia article here: http://en.wikipedia.org/wiki/P_versus_NP_problem
[edit] The responses below are correct. Proving P=NP means the world gets turned upside down. P != NP is already sort of assumed.
Looking at his page at HP Research, he has several other publications in legitimate areas, and seems to be a well qualified researcher.
He may be wrong in this paper, but there's no reason to suspect its a hoax or that he's some kind of kook (as many other comments have sort of implied).
b) The practical consequences of P=NP are immense. The practical consequences of P≠NP are that we can stop looking for computational unicorns and fairies.
We have for some time thought that P≠NP, but boy do people like those unicorns and fairies.
in 'a' above didn't you mean to write 'inequality of P and NP' ?
Similarly, most people believe the world is round, and we go around the Sun. This hasn't prevented serious flat-Earthers nor geocentrists from existing.
Computer Scientists have been assuming for years that P does not equal NP, so they've been doing research with that assumption already in place. Proving that the assumption is correct won't hugely change anything.
I'm not trying to knock down the greatness of this proof, but the repercussions aren't going to be that major.