Billions of honeybees have vanished worldwide. Dubbed “colony collapse disorder,” this has serious implications for farmers who rely on bees to pollinate their crops. An initial but much-discredited report (link #2) suggested that cell phone radiation was responsible, but now scientists are looking at a fungal infection as the likely culprit.
Update: According to the BBC, colony collapse disorder may be nonexistent and the big die-off is normal.
Update (2012-04-04): The cause of colony collapse disorder is still unknown, but researchers are narrowing in on a class of insecticides as being at least partly responsible.