http://www.alertnet.org/thenews/newsdesk/N01484543.htm
"The United States is poised to produce plutonium-238 for the first time since the end of the Cold War but it will be used for space missions, not weapons, officials said this week."

"Under the $300 million plan, the Idaho National Laboratory would produce 11 pounds (5 kg) of plutonium-238 a year for 30 years starting in 2011. The non-weapons-grade plutonium is used to power everything from satellites to deep space probes, leading industry insiders to call the finished product "space batteries."

The proposal calls for half the batteries to be earmarked for NASA projects and the rest for undisclosed national security purposes."

Nuclear batteries? Excellent. For lots of applications, only nuclear reactors can really compete with those, and those aren't exactly more simple or harmless.

Plutonium-238 in space missions seems a bit risky to me... Especially with the current amount of "incidents" surrounding the launch vehicules.
But well in 2011 the space shuttle will ne replaced (or so they say)

>Plutonium-238 in space missions seems a bit risky to me... Especially with the current amount of "incidents" surrounding the launch vehicules.

The capsules are very well shielded against things going otherwise wrong. I believe the Russian Mars 99 mission managed to fail and put some Plutonium in the Pacific without measurable problems.

Also, it's good to realize that we can't send probes outside the asteroid belt without some kind of nuclear power (I think, at least). Nuclear solutions are absolutely unequalled as long as we have to launch everything from Earth.