http://ashartus.wordpress.com/2011/07/04/cell-phones-and-cancer-revisited/
"Ashartus" reviews two recent meta-analyses of mobile phone cancer risk. One study found increased risk in the highest dosage group - extreme phoners - but lowered risk elsewhere. This lowered risk is likely an artifact (we would think.) The second study found no increased risk. The data sets had various problems like self selection, self estimation and classification problems. Some of the best data showed no risk and the epidemiology of the increased risk isn't quite as expected.
Overall, I stand by my original conclusion that there is no reason to panic unless brain cancer incidence rates start to increase, but at the same time if you’re an extremely heavy user of cell phones it probably wouldn’t hurt to take at least minimal precautions. Also of note, the IARC evaluation mentions that the electromagnetic field exposure from newer 3G phones (or from Bluetooth headsets) is about 100 times lower than for traditional cell phones, which means that even if the amount of cell phone usage continues to increase, exposure will likely decrease.