No, but it is recommended if frying.
Here is another of the great debates among Italian Americans: to salt or not to salt eggplant before cooking. I am referring to a process of sprinkling coarse salt on sliced eggplant and letting it sit in a colander for up to an hour. There are a couple of reasons for doing this. First, it draws out the bitter flavor that is inherent in eggplant. This is really more applicable to bigger eggplant; the baby variety is much less bitter. Second, is to draw out a lot of the liquid so the eggplant isn’t soggy after cooking. Many will argue that this process is unnecessary, and that there is very little difference afterwards.
Here is a great Los Angeles Times article that attempts to settle the debate with an experiment with eggplants that have been both salted and unsalted in a number of popular preparations. The findings? Other than a smoother texture when frying, there really isn’t a large difference in flavor by salting. Now we know.