I know a lot of lacto-ovo vegetarians consume honey, but I've never heard somebody claiming to be a vegan say they eat it. Bees are animals - therefore honey is an animal product, and you can't consider yourself vegan if you use any animal products.
Some people may not care if bees are enslaved, manipulated, killed (beekeepers often kill off their bees before winter, and kill the Queen before she is due to die to keep control of the hive), and the honey they work hard to produce stole - after all, they're insects, right? Not real animals. Not as important as cows or chickens. This is the same line of reasoning omnivores use when distinguishing pets from livestock. But there is some research suggesting bees are intelligent, which I'm sure you can find if you Google it, and that they are very capable of feeling pain.
Besides - honey doesn't taste that great and isn't a part of many products, so it's not hard to cut it out. The idea of eating bees regurgitation disgusts me, anyway.