For the first time, the majority of adult mobile-phone subscribers in the U.S. are now using smartphones, according to a recent report from Nielsen. But smartphone ownership dominates by just a slim margin, which means a lot of people are still using regular old cellphones. Some people may not feel the need to run lots of apps or to be connected to email all the time, while others may not be able to afford high-end smartphones, which can cost hundreds of dollars — not including the monthly data plans. Read the full story at All Things D.