The AP story "Card Counting iPhone application prompts Nevada to warn casinos" is about an application called A Blackjack Card Counter (iTunes, $2) which which ruffled more than a few feathers when it debuted the App Store.
The app allows you to improve your Blackjack odds by keeping a running count of which cards are left in the shoe. The theory is that knowing "the count" allows blackjack players to determine when they are likely to win a hand and adjust their bets accordingly.
And the casinos are mad as hell about it.
Nevada learned about the iPhone and iPod Touch app from gambling regulators in California, where officials at an Indian casino found customers using it and tipped state authorities.
Regulators have issues a warning to Las Vegas casino operators about the app and Atlantic City operators have also been put on notice. The Huffington Post notes that card counting by players is not illegal in Nevada but using a device to count cards is considered a felony.
I guess I know what I'm doing this weekend :)
Update: For more information on counting cards, I recommend Ben Mezrich's "Bringing Down the House: The Inside Story of Six MIT Students Who Took Vegas for Millions" which is available on Amazon and Google Books.
Update 2: Another "card counting" app, called Card Counter is bubbling up with all the buzz over ABCC. However it should be noted that Card Counter is meant to teach you how to count cards, while ABCC allows you to count cards live on the iPhone. Big difference.