Scientists, it seems, have proven that bumblebees cannot fly.
The meme circulates every so often to demonstrate various things. It can be a paean to the power of believing in yourself like the scientist-defying bee. It can be used to point out the ostensible Popean dangers of too much knowledge, or it can be testimony to the ivory-towerness of science. It can even be spread in aid of religious fundamentalism, like the missing day story: God knows bees can fly, but godless scientists don't.
The truth of the matter is a little complicated, as truths so often are.
Here's the deal, according to a post made to the newsgroup sci.aeronautics on October 9, 1996: scientists never discovered that bees can't fly. They have found that applying certain aerodynamic models to bees produces that result. Then they decide that, well, those models don't work for bees -- in other words, bees don't fly like that, they fly some other way.
Scientists, as a rule, aren't stupid. They know that bumblebees fly. They also, mirabile dictu, know that science can't explain everything. That is why they are scientists -- to increase the number of things science can explain.
However, flying bees is in that latter category already: Observation of bumblebees in flight shows the application of unsteady lift processes.