This just in: Vista will slip to '07.
First, my theory is that there's no way they are slipping only a couple of weeks. This far out, you don't have even close to that level of granularity in the predictability of your launch date.
Instead, their announcement to that fact is a move, in my opinion, to take the pressure off Christmas with this move so that vendors won't scream bloody murder this Summer when MSFT announces the real release date of Summer '07.
So what does this mean for Apple? Opportunity. Perhaps the most prime opportunity in their history.
Here's the play: Launch the next version of OSX with tons of gee-wiz features just before Vista launches, and do it on a platform-independent basis. Include in the OS the ability to launch Windows apps natively on the Intel Core chip, and it's a no-brainer for people. Upgrade to Vista which has a 2-year-old feature set (by the time it ships), or Switch to OSX which can run the same apps natively and do so on your existing hardware: it's not even a fair fight.
Apple has just been handed a gift. Vista slipping right into Apple's 18-month revision cycle represents a unique point in Apple's history where they can finally break out of their niche market.
Think about it.