Smart meters relay information on how much electricity is being used or generated by an individual building at intervals of about 15 minutes. Thus the utility can reduce the fossil-fueled generators they need to have on spinning reserve. We can use more renewable energy such as solar and wind if we deploy smart meters.
A University of California study debunked accusations against smart meters. Their results: Wireless smart meters emit much less radio frequency than microwaves and cellphones; current FCC standards protect people from thermal damage from RF; and there are no scientifically confirmed nonthermal effects from RF
RF is long wave, like the radio broadcasts, and completely different from ionizing radiation like X-rays, which are very short waves. RF can heat up tissue at sufficiently high power levels (like microwave ovens) but it does not knock electrons off molecules as do X-rays. These are at opposite ends of the spectrum. Those who would ban smart meters should first ban cellphones and microwaves and then broadcast radio stations.
Don't listen to uninformed fearmongering and Internet rumors. Smart meters are good tool to cut our imported oil use.