IIRC that might have been canceled because some people's first maps were actually pretty good and might have not gotten much attention because they were "New Mappers." It's a good idea honestly so people don't get so damn mean over someone's first map.
That was explained. 'New Mappers' is basically a less derogatory euphemism for 'Box maps'. Of course anyone who spends more than 5 mins in Radiant, regardless of whether it's his first or 10th map, would qualify for the normal releases section. A rating system (on the forums, I know this is going to be implemented in the UGX Launcher or w/e) of like 10 stars would be a fantastic idea I think, but I've said all this before anyway.