The GeeksAreSexy Blog has a posting about health issues surrounding wireless networks, including wi-fi. It includes a list of recommendations if you want to remain safe.
I wonder if employers will soon find themselves being sued by employees attributing illnesses to RF exposure from wireless networks used in the workplace. Personally, I like to put such things in perspective. Most wi-fi transmitters emit 30-40 milliwatts of signal strength. This is probably comparable to the RF output of most cordless telephones used at home. Also, in terms of frequency, most cordless phones sold these days also operate at 2.4 gigahertz.
I do note that a few high powered adapters and access points may emit up to 200-300 milliwatts. However, even this compares favorably to cell phones that typically radiate up to 600 milliwatts of juice (or even up to 1-2 watts) and which are typically held much closer to an individual’s head (although cell phones are not transmitting all of the time and can automatically scale down their power output when located close to a cell tower).