Playoffs?  Don't talk about playoffs- you kidding me?  Playoffs?
But seriously, the Boston talk radio people actually made a good point (it happens sometimes) about the ALDS this year- one of the two series has enough off days that you can pitch all 5 games with just a 3 man rotation and still have everyone on regular rest.  The ALCS, you can go with 3 men if you're willing to pitch games 1 and 4 with just 3 days rest (then game 7 on regular rest.)  In all series there are never 3 games in a row- the bullpen should be well rested and Joba should be available for most games.

The Sox radio guys said Boston would probably stick with a 4 man rotation in all series because they have the depth- but what should NY do?  I think in the ALDS there's no question you go with 3 men- Wang, Pettitte, Clemens, Wang, Pettitte, and you have Andy pitching the two most important games.  That's moot if NY ends up in the series scheduled with one less off day, since then someone has to go on short rest.
The ALCS is a tougher call- you'd like to get your #1 in 3 times, but your number 3 is exposed twice anyway, so it's not as much of a benefit to go with only 3 starters.  Probably go with 4 men and have your 1&5 starter available from the bullpen for game 7.