Last time I came, I put my backpack through the scanner. It had my laptop, camera, and iPod in it at least. I'm guessing my phone was in my pocket, but I don't remember. A worker pulled me to the side, asked where I was from and for my passport, and what I was doing in Argentina. The entire exchange took about a minute and I was on my way with no problems.
I had some friends and family come in later, with the same sort of stuff, and they said no one said a word to them. Put the iPhone in your pocket, and they'll never bother you, unless something sets you off (trying to bring in tons of electronics, especially anything new).