I'm a Card Room Dealer in a small casino in Washington state. We've known about iPhone apps for Card Counting for a couple months, so I'm a little surprised that it's taken this long for an official warning to go out from the Gaming Commission in Nevada.
In most Casinos you're not allowed to use or even have out a phone or other electronic device while at the table. Poker is usually different and phones are allowed, but never at a Blackjack table.