Wow - I think this is great news for both the 3.5 and 4e crowds.
For the 3e folks, this means quality support for the line into the near future, as well as Paizo's commitment to evolve the game. There are many of us 3e fans who recognize the warts of the system and have no issues with its evolution - but just don't find 4e the right solution for us.
For the 4e folks, they still get quality 3rd party support through Necromancer - possibly some Paizo support in the future (perhaps this is why they recently retired their 'Gamemastery' brand). Best of all, this could produce some real competition into the RPG market - which I think is good for both WotC, Paizo, and all the 3e/4e players.
I have no doubt that 4e will be a great product - but I do think that WotC has lost some of its customer focus in the past few years. This could sharpen up everyone's game, raise everyone's standards and perhaps even grow the RPG category. Competition could be good for the industry.
To me this looks like having it all.