When I was at the Sammi concert last month, I noticed a few shining lights waving side to side on the left section near the stage. Later on there were a few more to the right. Pretty soon, the whole stadium was filled with people waving their smartphones around with the camera flash turned on. I thought, this is pretty cool! Not quite the colourful batons that people wave around at the concerts in Hong Kong, but pretty creative. I remember years ago, we just flipped open our phones and had the dull ambient glow of our screens to wave around, but know we have these super bright (almost blinding if you're looking right at one) lights with us wherever we go. I bet the guys that decided to put the flashes into cell phones never dreamed that they could be used this way!
Then, look at all the pictures and videos that get posted online, sometimes instantly, from concerts and you'll find most of them are taken with people's cell phones.
I would even venture to say that the majority of the people attending a concert will take out their cell phone and use it for one reason or another!