Called Selune by the natives of Toril, the inhabitants of the moon actually refer to it as Leira after the former goddess of deception who protects their homeland with a giant illusion that makes it appear to be a crater strewn wasteland. I'm not sure how her death and Cyric's takeover of her portfolio may have changed this situation. I can't remember much about what's actually going on there under the illusion. I believe the Tears of Selune (the nearby asteroid field) is inhabited by secret bases of space pirates, etc., and is one of a few possible locations for the asteroid city known as the Rock of Bral.
All this info comes from the Spelljammer supplements Realmspace and the Rock of Bral. I have them at home, email me if you're interested in more details and I'll flip through them a little bit one of these days.