Ars technica examines the available information about the dangers of exposure to WiFi radiation. Short answer: Yes it's possible that Vampire JFK might have assassinated Princess Di to keep the Illuminati from using her to spawn an alien baby to start the Rapture, and WiFi radiation might be making your joints ache. It's just not very likely.
The initial report in the Times suggests that clearer data will come from an ongoing double-blind study, but WiFi Net News has found that a study of this sort has already been published. Those claiming to be radiation-sensitive were found to have their symptoms correlate with being informed of radiation exposure, regardless of whether any radiation sources were active. Thus, general health studies have shown no overall problems with cellphone-like radiation, and claims that there is a subpopulation that's uniquely sensitive don't seem to hold up.