Jeff Foust notes that there’s surprisingly little opposition to the RTGs in the upcoming New Horizons Mission (with some interesting discussion in his comments section).
I think that his take is right–back in 1997, when Cassini launched, loony leftists didn’t have a lot of better things to do, but now they’re so consumed with the war and George Bush that they don’t have the time or energy to focus on non-issues like this. As I pointed out in comments over there, when even perennial loony tune Bruce Gagnon doesn’t have time to organize anything against it, no one else will, either.
[Update a few minutes later]
Thomas James (Bruce’s occasional nemesis) has more New Horizons info.