There are only two types of true nonstick cookware: PTFE and nonstick ceramic--and nonstick ceramic is not the same as traditional types of ceramics and stoneware.
Thus, other than the new nonstick ceramics and PTFE cookware, stoneware cookware is not nonstick.
However, most stoneware surfaces--whether porcelain, enamel, or glass--are considered semi-nonstick; that is, they are smooth surfaces that clean up easily.
High-end enamel, such as that found on le Creuset, tends to have some of the easiest cleanup among surfaces that aren't officially nonstick (if you're trying to avoid chemicals found in nonstick cookware, this is a good fact to know).
Even better, those stoneware surfaces are tough, so you can use abrasive sponges on them to remove cooked-on gunk. You may want to avoid doing this unless absolutely necessary because it can leave scratches--try soaking instead--but if you have to, you can do it without harming the coating.