I heard about this one at my LGS the other day, and it sounds super counterintuitive so I had to double-check it here:

A player casts Show and Tell. A player (possibly the same player) puts Pithing Needle into play. Does the player who put Needle into play get to see what card was put in by the other player before deciding what to call with Needle?

According to the person I heard this from, the depends on whose turn it is; if NAP is putting in the Pithing Needle, he gets to see what AP put in, but if AP puts in the Needle, he goes in blind.

The person you heard that from is incorrect. A player putting Pithing Needle onto the battlefield off of Show and Tell will know what the other player is putting onto the battlefield at the time he or she names a card, regardless of whose turn it is.