Sir John Beddington has commissioned a summary of the science of global warming at the GO Science website. My impression, based on a brief perusal of the contents, is that it's largely a standard-issue "we're all going to fry" kind of thing, but perhaps a more detailed look will prove me wrong. This was interesting though:
The fact that uncertainty exists in climate science, as it does in other fields, does not negate the value of the evidence – and it is important to recognise that uncertainty may go in both (or a number of) directions. But an appreciation of the nature and degree of uncertainty is critical if the science is to properly inform decision-making. Indeed, that is what much scientific endeavour is about, describing both what is known and where our understanding is imperfect, and placing “error bars” on the knowledge we have.
This appears to be an admission that we don't as yet have error bars on "the knowledge we have". An important statement, I would say.