Operation Payback was another of Valve's experiments with 'games as services' and paying community creators, and a jolly successful one at that: Counter-Strike: Global Offensive community mappers earned over $150,000 from players paying $6 to run around their seven maps on Valve's official servers. So huzzah, it's been extended for another month, until August 31.
The original run was from April 25 to July 1. Note that the $150k is only the mappers' share and we don't know what Valve's cut of the ticket price is, but we can say that over 25,000 people paid $5.99 for a pass, at the very least. Which is certainly quite a few.
Valve noted that it's already looking at more fan-made maps for a second Operation.
If you've already bought a pass, hey, it's still good for the extra month. If you want in, hit the official site for more info on buying a pass. As well as access to the maps, you get a 'challenge coin' to show off, which ranks up the more you play them.
While Valve might have its fans making silly hats and magic swords in other games, CS: GO is a pretty straight-faced affair so maps are perhaps the best way it can get 'free' content and pay a little back. It does sell map 'stamps' in Team Fortress 2 for players to pay the makers of individual maps, but CS: GO having official servers gives Valve another way to experiment--quite successfully, evidently.