Just in case you haven't heard of the new condition, it's called cell phone elbow or, more commonly referred to in medical terms as "cubital tunnel syndrome."
Here's a story about it from CBS News.
"The latest over use or repetitive motion injury to join the digital age list is cell phone elbow. It is caused by too much bending of your arm to put a cell phone to your ear. This bending compresses the ulnar nerve, which runs along the bony bump on the inside of the elbow."
I have seen many "cubital tunnel" cases in my practice, but none using the theory of too much cell phone use. However, I can see how this might easily be a winnable case. In my own experience of holding a cell phone while driving (before I purchased a "hands free" unit) it would only take about 5 to 10 minutes before my arm became sore.