I wonder how much influence the dental insurance companies had in these findings. Insurance companies don't like to pay for tooth colored/resin fillings in posterior teeth, since they cost more than amalgams. And even if the insurance pays for the resin fillings at all, they only reimburse the dentist the amount they would pay for an amalgam. The patient is then often responsible for the difference in cost. The new amalgam fillings contain MUCH less mercury than earlier years. Amalgam is still a good restorative material in many situations and 100 years of history seems to indicate that amalgam is still generally safe and effective.
That's for sure. But it's worth paying the difference - you don't really want those ugly dark things in your mouth even if they prove to be harmless.
That's not to mention those nifty radio stations you can pick up with metal fillings now and then...