Thorium and nuclear reactors talk has been around for a few years - it's been discussed on MV even(you can do the search) .. I'm not sure why the energy dept has not invested more time and money and research into this - political and lobbyist reason - no doubt.
I would like to see more done on thorium reactors, but I think the impediment to it isn't Luddite eco-nuts, but Big Energy, which has its collective heart set on big uranium reactors. They have already figured out how to skimp and cheat on the now watered down safety regulations for that kind of reactor and don't want to start over with a totally new design.
And, as we have seen in Japan earlier this year, there is practically nothing that can go wrong when watered down safety standards meet the real world on a bad day. 
I don't think that's the issue. I think that throium, despite being safer, has all the risk management costs as a uranium reactor, plus all the startup costs of implementing the new thorium reactor technology.
Margins are pretty thin on a nuclear reactor, so without subsidies, or regulation changes that bring down total cost of construction and operation, it's probably stalled until enough uranium reactors go online to bring up fuel and disposal costs through competition.
The US probably won't lead the way because the supply/demand curve for the critical parts doesn't operate across borders without restrictions. Russia, china and India will likely beat us to it because there is much more demand competition in their borders. We have bigger uranium supplies and minimal nuclear plant construction demands relative to them, so we will lag behind. OTOH, it means we get to learn form their mistakes.
It still beats solar power fields, which even subsidized can't turn a profit due to property taxes (even heavily discounted property taxes). Which is why the most profitable solar sector is energy traders getting into net metering only, "zero cost" leases. They buy huge energy contracts, sell you electricity at a couple cents over the discounted rate in open markets, but less than the wire owning utility, install the panels on your home, and sell you the electricity coming in at say $0.11 per kwh while selling the panels' electricity to the utility for $0.138 or whatever their rate is per kwh.
and that most green tech sucks in the short and long run at this point.
Wind and solar have poor energy density. It's just their nature. I don't see why the utilities aren't getting in on the same setup I described above. It'd help make their grid more robust and fault tolerant without having to build more generating capacity or laying miles of wire. As a generating station or co-gen, solar does still suck.
Wind is wind. It's intermittent and difuse.
Tidal is better. energy densities are higher, and it works in both directions only varying output over time. All the significant ones to date are stream generators, and limited to certain geographic areas without serious modification of the coast. Barrage generators offer a less drastic option by not having to enclose an area, but I don't think any of those are complete as yet.
wave generators look like they might have a lot to offer. Much less intermittent, and much more energy density than either solar or wind. But as an engineering task, we've only spent about 6-7 years playing with the idea with serious computer modeling, and about 3 testing with large scale prototypes in the actual oceans (sort of, the first was launched in 2008 and closed due to bankruptcy of the company funding it, and the other one opened in 2010).
Better density is realtive though. For example, my nearby nuke plant at indian point produces 2000 megawatts from a 239 acre facility. The wave generators require 420 m/sq per unit, no idea on the spacing. Assuming the spacing between units is zero, for 2000 MW, you would need about 286 acres of ocean floor. cordoned off to 50m below the water surface. Which isn't too bad. Theoretically solar is 276 acres for 2000 megawats, but show me anyone actually doing that as a an average for a year.
Basic problem with Thorium is thst there isn't currently a working reactor or even a design that can be licensed. Even if we started today, it would be 20 years before we would have one.
thebaron
With new reactor designs and better source of radiative source will make them even safer, not that the luddite econo-nuts will care...