Only 45% of those surveyed agreed with the statement that "Global warming is a proven fact and is mostly caused by emissions from cars and industrial facilities such as power plants and factories." That number is down from 54% who agreed with the statement in June of last year and in May of 2007.
Meanwhile, the number of people who agreed with the statement that "Global warming is a theory that has not yet been proven" jumped to 31% in the current survey, up eight points from June 2008.
Some will certainly portray this as a great tragedy for science and will portray it as a victory for ignorance over scientific fact. On the other side, some people will claim this as a great victory over the world-wide conspiracy.
The truth is far from both.
Regardless of how you feel about man-made global warming, the truth is that it is not a proven fact. To quote from the APS ad-hoc committee formed to review the APS statement on global warming
And that's from a committee that (correctly) rejected an application to significantly revise the current APS statement on global warming to make it anti-anthropogenic global warming. So people have moved away from the un-scientific view that global warming is a 'proven fact' to one where it is 'only' a 'theory'.
Although the evidence is strong that climate warming has anthropogenic sources, as described above, anthropogenic warming is not a proven fact.[emphasis theirs!]
On re-reading it, its possible that one could weasel around and say that the poll only references "global warming" and not the "anthropogenic global warming" that the APS ad-hoc committee is referring to, but I think its generally understood by the public in the context of the question to mean that "global warming" was referring to the 'man-made' kind.