I may be stepping into the sar-chasm here, but for those who may have actually been confused, we are not talking about being able to burn conventional biological waste. We are talking about being able to "burn" transuranic waste products that result from the fission of uranium-235. Fast neutrons have a high enough energy level that they can initiate fission a significant percent of the time in isotopes that water-based thermal reactors won't. This does not mean that the resulting waste isn't going to be radioactive, but fast reactors can in principle reduce the waste to relatively short half-life isotopes. It also gets more energy out of a given mass of uranium by being able to get energy out of some of the fissile byproducts themselves.
In short, it is the kind of reactor we ought to be building, be it these new small-scale portables or the gigantic 1.5 GW variety. It is a constant source of amazement to me that we invested all the time and effort to research fast neutron reactors at the Idaho National Lab, proved that it worked freaking awesome well, and then completely failed to use anything that was learned there. Almost all of the proposed new reactors I have heard about are still going to use water-cooled thermal reactors, with all of their inherent safety problems and dependence on a fuel reprocessing cycle that is not only wasteful, but is also incredibly dirty, insecure, and flat-out dangerous.
