“Mark Landler in the NYT”:http://www.nytimes.com/2009/04/15/world/asia/15korea.html asked Sig Hecker for his view:

Siegfried S. Hecker, a professor at Stanford University who has extensively toured the plant, said it would take six months to rebuild the cooling tower that North Korea blew up in June 2008 as part of an earlier agreement.

But Dr. Hecker said the North Koreans could begin reprocessing plutonium from an existing cache in a couple of weeks. That would allow them to make at least one additional bomb, he said, which might embolden them to conduct another test and refine their bomb-making expertise.

“With Yongbyon disabled, it meant no more bombs and no better bombs,” Dr. Hecker said.

The North had earlier agreed in principle to give up its nuclear material and any weapons, but talks on how to reach that goal stalled. During the Bush administration, North Korea is believed to have produced enough bomb-grade plutonium for six or more nuclear weapons.

Dr. Hecker said that throwing out inspectors also raised the risk that North Korea could sell nuclear material to other countries.

The possibility of a second nuclear test -was mooted at least as early as last month- has been mooted “recently”:http://english.yonhapnews.co.kr/northkorea/2009/03/26/62/0401000000AEN20090326007400315F.HTML.

Would it get the North Koreans anything? As mentioned above, it could help them to validate a bomb design. But would it soften up the U.S. or the neighbors? I doubt it.