In the industry (Score 5, Informative)

Finally, after years of lurking, a subject I can speak with authority on.
I actually got to speak to a Georgia House committee on the subject of smart meters, since I work for one of the major manufacturers. Here are some of the things I told them...
Our meters use licensed 900Mhz FSK (not spread spectrum) bursts. An average electric meter transmits 6 times a day with 1 watt EIRP (off a PCB antenna in the meter), in bursts of about 180ms. Total on-air time is nominally 1 second per meter per day.
As for privacy, we use symmetric AES-256 encryption with per-meter keys for both uplink and downlink to the meters (our meters are twoway-capable). Keys are rotated generally every three months (yes, imagine rotating 4+ million encryption keys every few months, over a system with an aggregate bandwidth of about 12kb/s).
We sell a "remote-disconnect" option in our meters, but it's expensive and only used by electric companies in limited situations. While we can trigger a remote disconnect, in the interest of safety we cannot re-energize a meter without a very complicated dance. Instead, we send an arm-for-reengize command, and then tell the consumer to take their TV remote control outside and point it at the meter and hit the "POWER" button. An IR receiver in the meter face then causes the meter to re-energize.
One of the big complaints (after they get past the RF) of the anti-smart meter groups is the use of "dirty switching power supplies". According to the anti-smart-meter web sites, these switching power supplies cause surges on the AC mains, which somehow increase cancer risks up to 13 times. The power supplies in our meters are actually certified under 3 different FCC type ratings, and are somewhere north of 95% efficient buck-boost supplies. Since the load of the metrology and RF boards in the meter is minuscule, smart meters generally only draw milliwatts while running, and the chances of inducing large spikes onto the mains is non-existent.
I got to meet some of the people behind the anti-smart-meter campaigns. For the most part, they're nice elderly ladies who get their view of the world from Pat Robertson and Fox news. They crave some cause in their life, are experiencing health issues generally related to aging and unhealthy choices, and find any new technology (especially hard-to-understand, mandatory-use technology like smart meters) scary and use it as a good scapegoat for their health worries. Everyone here realizes that a web page is the ultimate printing press, and with enough Googling you can find some "expert" pushing some kind of "science" to support pretty much any view you wish to cling to. It's embarrassingly easy to put together a semi-literate sounding alarmist web page backed up by flaky pseudo-science and gather like-minded people to your way of thinking.

Bottom line is, as an electrical engineer, an extra class amateur radio operator, and a father, there are about a million things my kids run across every day that are more damaging or dangerous than smart meters. Most of those are naturally occurring (sunlight kills more people in a year via skin cancer than every smart meter I've ever played a part in will kill in a thousand years). If you need something to stress about or blame your poor health or weird medical condition on, please find a better scapegoat than smart meters.