Everything you could want to know about the NH recount is here:
http://www.wired.com/news/evote/0,2645,65736-2,00.html?tw=wn_story_page_next1
The article covers why NH was chosen, why they think the specific precincts that were selected were worth further investigating, how the recounts will be done, when we can expect to hear some further news, etc.
Bottom line, as I read it - they don't know if there was fraud, honest error or just a fair count. The statistical anomalies are significant enough to raise questions, and they feel that doing a recount will let us resolve the questions one way or the other, which is positive no matter what the outcome. I agree.