Given that I have received probably over 30 submissions on using Exposé in slow motion, I deciced to give in and run a hint on it ... I actually didn't think it was worth running on its own, given previous hints (1, 2) regarding slow motion effects, as well as an indirect mentiond of Exposé in slow motion in the Enable the floating Exposé blob hint ... but since it keeps getting submitted, here it is, officially documented:
To view Exposé effects in slow motion, simply hold down the Shift key before hitting any of its activation keys (F9, F10, F11 by default).
Mac OS X Hints
http://hints.macworld.com/article.php?story=20031215072054934