Mac App is still an Apple product, and was at least recently still available from Apple. I just went looking for it on Apple Dev and couldn't find it, but I think it is still there somewhere. Apple still hosts the mac app developers list http://www.lists.apple.com/mailman/listinfo/macapp-dev. MacApp is still alive and currently works great for development in OS X. It is supported privately. See http://www.clubmacapp.com/.