By saying they'll price drop the PS3 we could get a 360 rumor repeat. A lot of people ignored buying a 360 because of the rumored $100 price drop. A rumor like this can go both ways. Sony needs to confirm it fast, or lose even more potential profit as people will wait.
Example: If Sony said they'd make the PS3 $200 next year, I'd consider buying it. Now let's say it doesn't drop in price. I'm still in the price drop mind set, and I'll be even more encouraged to wait. This is why I didn't buy a 360 yet.