For anyone that's unfamiliar with Greenlight, this notice essentially means that Steam has accepted Sumo! to go on to their service, and it should be publicly available via Steam within a short period of time.
As it is, though, I'm midway through porting Sumo to another version of the Game Maker, so it may or may not be a little while until everything is set. We'll see.
I thoroughly plan on doing a writeup on my experiences in Greenlight to hopefully help anyone else out that's going to try to get through. Keep your eyes out!