Aren't we going to take into account the PS3s that are sold solely for it's blu-ray capability. There's a lot of people out there who don't game but just watch blu-ray movies.
I'm guessing that the majority of the 80% sales increase are due to 360 owners. PS3 fanboys wouldn't wait for MGS4 to come out before purchasing a console. MGS4 is one of the best games out there and even I would purchase a PS3 just to play this game. I predict that sales should decrease significantly in the following month.