It's a dirty, dirty move. Its whole reason for existence is to move the rest of the outdated product so they can usher in a newer, PS2-Emotion Engine-less version with a whopping 20GB more HDD space and still charge the same price as before. It's a dick move. And I hope folks will look into it, but Sony knows that 75% of the world's population are retards and won't look past the $100 price drop. I, too thought it was cool until I saw the blatant reason WHY. And that, dear friends, is why as bad as I want to play MGS4, I'll wait for the inevitable 360 port - even if they do sell a ton of systems at $499, they still won't be able to sell enough of them to warrant the exclusive release of a high-profile title like that without the company giving a substantial monetary boost to the developer(s) in question.
That's a conundrum for sure - great business move with a total lack of ethics behind it - it's more of a bait and switch than a price cut.