Card Tracking in Poker and Breaking Vegas

Playing a little poker at f-woods over the weekend could not help but notice the dealer would consistently show you the bottom card before shuffling. I would not think you could do much by knowing the location of one card but in blackjack this can give you a powerful edge.
Anybody ever heard anything about this? Is sort of a rambling post but hopefully somebody gets the point and maybe could explain. Never been a card tracker so dont know about the various shuffles and how this relates to poker i asuume the edge could never be quite like blackjack and hopefully the casinos would stop this if people were using this tactic.