According to some new research by Swiss researcher Daniel Favre, honey bees can tell when cell phones nearby are making or receiving calls. This causes them to engage in something called "piping" where they make sounds to signal other members of the hive that there is danger. From there, the bees decide whether to flee or swarm. Favre tested this with cell phones near beehives and noticed it took the bees many hours to return to a normal state and calm down after the phones were silenced. So massive amounts of cell phone use around a beehive (which...why would you want to do that in the first place?) could cause problems. This is interesting research although Favre's findings aren't quite as dramatic as they're being reported some places. He didn't find that cell phones are responsible for the rash of bee deaths around the country.
The obvious solution here is to make much tinier cell phones that the bees themselves can operate so confusion is avoided.