I was surprised to read that regarding the slot machine as well. To my eye in Vegas, which I imagine is a bit of a standard bearer for casino security, they've caught up with today's phone culture. In the past, even a glance at your phone to check the time got a stern reaction from any gaming employee. Now, they seem to parse whether or not you're engaged in nefarious activity, or on it for too long, before they say anything. That is to say, a text to your friends of "I'm near the front" doesn't seem to rattle every dealer. And casual pictures near machines or neutral parts of the gaming floor seem to be happening.
YMMV.
-Jason