Originally posted by Egadd
For a warning system, I guess the mods (or perhaps the bots) could PM you when your hack gets accepted, but that's just it. There's no need to create a thread once a hack is accepted only saying 'your hack was accepted' and small aditional notes. If the mod wants to say something about the hack, a review in the hack might work.
Besides, like EG mentioned, that's not SO quietly. There's the latest hacks list on the main page, and warn a new hack twice would be pointless. That's an excellent place to those who want to play something new BTW.
E: fixed typo.