I blogged about this issue before and I'm changing my mind about how worried I should be.
Pittburgh Cancer Center released an advisory to limit the usage of cell phones "to be on the safe side". As it turns out, there's still no conclusive evidence of links between long term cell-phone usage and cancer.
At least from this article, it feels Dr. Herberman (who released the advisory) is basing his conclusions on biased, not-necessarily-peer-reviewed research. Look, doc, I appreciate your concerns, but going around spreading fear, rather than information, is usually not an awesome way of doing things.