(Updated Below)
I don't intend to sound off alarm bells, but the question does need to be asked, as we have seen signs of this in the past, such as in Ohio during the 2004 general election. I just spent the last two hours putting together a spreadsheet of the Democratic results of the NH primary for each town with almost all but a few towns reporting, and the results were somewhat surprising. (Note: This is also without including nearly 2500 write-ins due to time constraints.)
I say "somewhat" because some people will say this entirely foreseeable. What the informal statistics show is that Hillary Clinton received a 4.5% boost in towns using Diebold voting machines compared to towns that didn't. Meanwhile, Obama was hurt in these towns showing a 2.5% decrease in the Diebold towns.
One thing to note before looking too much into these statistics is that the Diebold machines were concentrated in the less rural areas. I say less rural, because there really is no "urban" areas in New Hampshire. This then begs the question as to whether rural voters really were more likely to vote for Obama than Clinton.
The possibility of election fraud is even more important considering the predictions heading into NH primaries. All the polls were showing Obama with at least a 7 point lead over Clinton, with a few showing a double-digit lead, which is no surprise considering Obama's win in Iowa over Clinton who placed third in the caucuses.
I don't have enough information or time to compare this data with anything else. No matter what, the results were still significantly closer than the blow-out that was predicted. Does this show election fraud? Right now I'm not sure, but the possibility definitely remains and must not be taken off the table.
Update: Some more statistics from the data shows that Obama in non-Diebold towns garnering 38.7% of the vote to Clinton's 36.2%. The results in Diebold towns show the exact opposite: Clinton with 40.7% of the vote and Obama with 36.2%. Not only are the positions swapped but the informal statistics have the second place candidate holding 36.2% in both cases, which could easily be a pure coincidence. What doesn't make a lot of sense to me right now and this could be a mathematical mistake on my part is where Clinton got the extra 2% of votes in Diebold towns. All the other numbers almost exact for every candidate, even Edwards who recieved 17% of the vote in Diebold towns compared to 17.6% in non-Diebold towns. That still doesn't make up for the extra 2% vote Clinton is receiving when she leads in certain towns compared to when Obama has the lead.