How many molecules in a pizza?
Number of chess positions and molecules in the universe

Ye i think i'll just take a quick guess....Ermmm.... 10 to the power of pepperoni..Right now i'm starvin..

A related conjecture:
http://www.chess.com/forum/view/more-puzzles/fermats-last-pizza
nice! they had a good sense of humour back then.

Well, the thing to remember about tablebases is that the positions (which presumably couldn't actually be stored on a single atom) are only the nodes -- the legal connections between them (the edges) are also necessary to capture. The difference between the two is (necessarily) the number of legal positions vs. the number of legal games.
Presumably the theory above only considers the nodes (positions).
and i thought the stalemate thread was bad!