This has been bothering me all day.
One of my contemporaries repeatedly caused a piece of silk to vanish in to his fist then re-appear during a slow calculus class today, and I can't for the life of me figure out how he did it 
Which brings me to my next point - why are there no websites documenting magic tricks of even this caliber? Why is it that I can find numerous bomb recipes, but not a decent how-to on palming a piece of silk ribbon?!
Anyone? 
First, the reason that you cannot find any free info on the 'Net is that 'magic' is a cash generating enterprise. Beleive it or not, illusionists can make a pretty decent living, and even bad ones don't want everyone to know how to make things vanish. Your contemporary probably learned the trick first-hand, as that is how most magic is taught.
Second, it's not "Where did that ribbon go?"... Its "Where didn't that ribbon go?"... You know that it is no longer in the hand that you thought it was in. What you don't know is how it got into the other hand. By paying atttention to one, you allow the other to do the work unseen. Sleight of hand/illusionism/magic is nothing but misdirection of attention.
With all that said, I suck at performing that kind of thing. But magicians and illusionists have berated me for walking up to them after a performance and saying something like, "So where did you get the idea for the faux panel?"
The Reverend hit it dead on. Even if you try not to be distracted and keep an "open mind" about what could be happening a really good illusionist will move so fast and smooth that following their motions is almost impossible.
I'd suggest telling the guy you were impressed and asking for more demonstrations. If he cares he probably won't just tell you how he did it, but you can probably convince him after a while.
Yeah, illusionists hate when you point out their tricks. When I was young, like 8-9 my brother and I were watching this illusionist outside a theater. We had just gotten a book of tricks and while we couldn't do them well we knew how they were done. This guy must've had the same book cause he did every trick we knew and almost no tricks we didn't. He just kept getting madder and madder as we shouted out how he did each trick.
Serves him right, trying to impress people with tricks from a kid's book.