The emails that were exposed are not trivial, and because of that, they do throw some doubt on our knowledge of the severity of human-caused global warming. The problem is that they indicate that some of the top researchers in the field have not been following the norms of correct scientific behavior.
The comments in the email do not reflect proper respect for the key concepts of the scientific method. The worst quote of all is the one about hiding the decline. Had one of my graduate students said something like that, he would no longer have me as his advisor. Scientific integrity means being candid about the weaknesses of your own analysis. You have to show all things that throw doubt on what you have concluded. This is a key part of the scientific method.
Phil Jones said he would use Michael Mann's "trick" to do this. I know exactly what he means by this (I am familiar with the data and the method of analysis; I've written about it), and it is not a valid mathematical trick -- it is a data presentation trick that will mislead the policy people who depend on the analysis into thinking the data are more consistent and dependable than they really are.
The emails are full of other "tricks" too -- such as ignoring the content of criticism, and instead saying it was not "peer reviewed". And then trying to interfere with the peer review system when it finally is reviewed.
These emails show that some of the top practitioners in climate analysis were not following the minimum standards of science. That means that we do have to doubt their other results. It doesn't make sense to argue that they were exposed for distorting only a small amount of the data. We need to have the data released -- in particular, all the details of the thermometer measurements over the past 150 years (and longer -- older data exist but have not been analyzed) so that the larger scientific community can analyze it all independently. This can happen quickly.
My own guess: that the global warming record will be vindicated. This guess is based on the fact that there has been no global warming over the past 12 years. To me that indicates that the record was accurately presented; no cheating. But once you have uncovered some cheating, you need to check everything.