Many months ago I installed this trackpad update for XP on my release unibody Macbook and immediately found it to BSOD each time I touched the pad. I reverted to last knwon good in disgust and have barely used Windows since, as the Bootcamp 2.1 driver is such a piece of crap (3 fingers for a right-click, even though it says 2?!!). I couldn't believe Apple would release such an awful driver.
However, I recently installed Windows 7 RC since it's very good and have been using it all day without a hitch, even with the trackpad update. Then I installed Skype - and bang! BSOD immediately, and each time I touch the pad without fail. Then I remembered that I had Skype on my XP install before I installed the trackpad update.
So, yes the driver is at fault obviously, but the trigger is unequivocably Skype. Sort it out Apple this is a joke! Claiming no support for Bootcamp isn't really on since for many it's the crutch that makes switching platforms acceptable.
Another thing that bothered me for ages was the stiffness of the trackpad click on the unibody, and I discovered today that you can loosen the tension using a screw inside the battery door. Finally, one of the other big niggles resolved. Just need this driver fixing now...