The meme that slavery is wrong in principal, as opposed to only being wrong when it happens to you, is definitely a product of the enlightenment.
That's true only under a highly contrived definition of the Enlightenment, which defines it more or less as the set of all intellectual trends in the 18th century that are in sufficient agreement with today's respectable opinion. (Admittedly, this is more or less how the term is used in today's standard cartoon history.)
In reality, the modern anti-slavery attitudes are due to the political (and military) victories of the abolitionist movements in the English-speaking world in the period 1807-1865. These were strongly religious in character, and influenced by the Enlightenment only insofar as all major intellectual trends influence each other to some degree.
From what I've heard, the enlightenment played into making American slavery as bad as it was. Since the enlightenment said that it was bad to enslave people, but slavery was very profitable, a pattern of rationalizations were built up that Africans were innately inferior and slavery was good for them.
I wanted to bring attention to two posts from Razib Khan's Discover magazine gene expression blog (some of you may have been readers of the still active original gnxp) on the polemic surrounding Pinker's The Better Angels of Our Nature.
Relative Angels and absolute Demons (and the related But peace does reign! )
I generally agree with some of his arguments, but found this quote especially as summing up some of my own sentiments: