Counting cards is the oldest trick in the gambler's arsenal when it comes to increasing the odds of a win at the casino table, and since the birth of Blackjack, card counters have turned to every sort of device known to man to help them manage the often complex, rapid-fire "count." (My favorite gizmo from yesteryear -- not that I've ever used one -- involves a tiny shoe-based computer you could operate with your toes.)
Now there's something far more sophisticated on the market, and anyone can get it for about $1.99. Blackjack Card Counter (along with at least one other application) is now available to anyone with an iPhone, and it's an awfully sophisticated way to surreptitiously keep tabs on what the count is -- the theory being that when there are more tens/face cards and Aces in the deck, you should bet more on the hand.
Of course, card counting computers are illegal, so Blackjack Card Counter can run in "stealth mode" with the screen off, vibrating when the count is in your favor to alert you to bet big. Users simply tap buttons corresponding to the type of cards that are used in play in order to feed data to the application so it can do the appropriate calculations.
Vegas has finally wised up to the scheme, after California casinos alerted the Nevada gaming board to the existence of the app. With pit bosses on the lookout, anyone caught using an iPhone (or any other device) to count cards can be arrested on the spot.
Cell phones are not actually illegal at gaming tables but most casinos have a policy against using them there. As the Las Vegas Review-Journal notes (story linked above), iPods and MP3 players are often permitted... but since these counters will run on the iPod Touch, rules might soon have to be changed again.