Well, for me, I flip flop as the issue goes along. I was a long time non-believer but started to sway when the whole 'scientific consensus' line was thrown around. I figured, 'well, if they all say it's true'.
Since then I'm more a non-believer in the AGW line as presented by the IPCC and some of it's main champions. This is not the same as being a person who doesn't believe in GW at all, far from it. I just find the predictions and catastrophe claims a bit rich and too much like fear mongering, in the same category as 'reds under the bed', 'WMD' and 'Terror Alerts' and who knows how many other scare campaings have been pumped up, held aloft and then quietly deflated over time. The whole thing has taken on a religious quality.
For the record, here's my problems with the current theories:
1. The predictions are all the result of computer models. As a programmer myself, I know how hard it is to have faith in the results of a program processing large amounts of data when there is no real way to check it. The release of the code from CRU has firmed this belief up considerably. It's clear these guys are not software geniuses.
2. While I have no complaint with the concept of carbon dioxide as a warming agent, we don't know enough about the concentrations needed to increase. Is the relationship linear, exponential, or subject to diminishing returns.
3. The AGW proponents often talk of runaway warming or positive feedback. How do we know there is no negative feedback? What if warming increases evaporation and cloud cover, and lowers temperatures over time? You've only got to spend a week in England to realise cloud cover can really affect temperatures. Remember all that fear mongering over a Nuclear winter?
4. Is it really known if warming is net negative for humans? Would the conversion of currently frozen lands into productive pasture outweigh loss of some farming land? Most of the change involved in Climate Change is seen as a negative, but all change involves wins for some and losses for others.
5. Are we talking about true Global Warming or just Arctic Warming? Because the old timers around where I live will tell you it was a lot hotter in the '30s and '40s than it is now.
I'm not pretending I have the answers. I just think there are more questions than answers, and that some of the facts and data thrown around are subject to wide prediction ranges, yet we always hear worst case scenarios.
Finally, my firm belief over the last 10 years has become that functioning economies are the most important factor of human life quality. You've only got to travel to a country with a non-functioning economy to see how bad life can get. With moribund economies, you get increases in crime, disease, death and an end to innovation. Only the strong and performing economies can afford the changes to lower polluting and sustainable energy sources. Printed money paying for uneconomic projects and empty promises aren't the way forwards, innovation and new ideas are. There should be more focus on the reward side (cash, prestige, positions) for those who come up with the answers rather than punishment (taxes, industry penalties, outright bans) for those continuing to use current technologies. You just can't tax or force people into prosperity - they have to take action themselves by rationaly deciding the better way forwards.
So, to answer the original question : the CRU leaks have pushed me further into skepticism when you see how far the grab for power and money has seeped into the whole thing, and how low the quality of the data is that these predictions and decisions is based on. Nobody, not the scientists, politicians or do-gooders are immune from the draw of power, money and the chance to rewrite society in their own plan.
[edit:just wanted to add one more thing. I don't like how you can be genuinely skeptical, and want to see more evidence, but you are immediately labelled a 'denier' and lumped in with the global-conspiracy theory people, creationists and other assorted non-thinkers. It's this in-or-out attitude that makes me uneasy. If you've got a genuinely true theory, then you should let people agree with you as they see the evidence and decide for themselves.]