Is bidding in contract bridge just a matter of applying a set of rules?
Wikipedia says that any bridge bidding system is a well-defined form of legal table talk:


  Each bidding system ascribes a meaning to every possible call by each member of a partnership, and presents a codified language which allows the players to exchange information about their card holdings.


That would seem to imply that there is no skill involved at all, but I think there's more to it than that.  I used to be a casual reader of the bridge quizzes printed in our newspaper.  They would tell stories of bridge tournaments where every table played the same hand, and different tables would arrive at slightly different contracts.  As the commenters have pointed out, there is some flexibility within the bidding system.  It's not an exact algorithm.  While everyone knows what your bid theoretically means in the context of your hand, you and partner still need to use that knowledge effectively to arrive at the most profitable contract.  The skill, therefore, is in correctly choosing the next bid, not in decoding the bids or deceiving your opponents.