Originally Posted by Jack Daniels
This is just not true. Multiple decks has nothing to do with counting cards except that you have to use larger numbers. Live blackjack is absolutely beatable. The only thing they've done, in some casinos but not all, is to introduce the continuous shuffler that keeps adding all used cards back into the shuffle. Not only is there never a break in the play since shuffling is continuous (more hands per hour), but they eliminate much of the advantage that you can actually gain over manually dealt blackjack with a discard pile. But if you don't think live blackjack using six decks is beatable at all, it's time to pick up a book...I'd recommend "Knock-out Blackjack" by Vancura/Fuchs.
counting cards still only give you a very very very very slight advantage, think like less then a percent right?
Card counting - Wikipedia, the free encyclopedia (http://en.wikipedia.org/wiki/Card_counting)
Blackjack played with perfect strategy typically offers a house edge of less than 0.50%, but a typical card counter who ranges his bets appropriately in a game with six decks will have an advantage of approximately 1% over the casino. This amount varies based on the counter's skill level and the playing conditions, and the variance in blackjack is high, so generating an hourly profit can take hundreds of hours of play. The deck will only have a positive enough count for the player to raise his bets 25% of the time. 
At a table where a player makes a $1,000 average bet, a 1% advantage means a player will win on average $10 per hand. This translates into an average hourly winning of $500 if the player is dealt 50 hands per hour.
With typical bet ranging, a player's variance
(http://en.wikipedia.org/wiki/Variance) per hour is normally almost one hundred times his average bet per hand, meaning that a player whose strategy yields an average profit of $50 per hour will likely face a variance in the neighborhood of $5000 per hour. Therefore, it is highly advisable for counters to set aside a large dedicated bankroll; one popular rule of thumb
(http://en.wikipedia.org/wiki/Rule_of_thumb) dictates a bankroll of 250 times the average bet per hand at count = 0.
Another interesting aspect of the probability of card counting is the fact that, at higher counts, the player's probability of winning a hand is actually lower than at lower counts - so that, with an optimal strategy, the player places his highest bets on hands whose probability of losing is actually the highest. The player's edge over the house on such hands comes not from his probability of winning the hands, but from his ability to perform certain actions, like doubling down and splitting, that are not available to the house.