Well, I don't know much about it but I think fluorescent bulbs are the ones that arn't suppose to generate heat to save you energy and stuff so I think it wouldn't generate a significant amount. Hope this helps.
Are you asking about the linear (tube) or compact (spiral)? The ballast for a linear fluorescent will generate some heat, but is usually located in a spot that doesn't direct much, if any, heat into the enclosure. Compacts will generate a bit more due to the ballast being located in the base of the bulb, in my frog tanks it is usually 4-6 degrees above ambient temp within about 6 inches of the bulbs.