The team at Valve working on Counter-Strike: Global Offensive have now put an end to the selling and trading of new container keys.
In a post on the official site, the Valve team said as of now all keys purchased in-game are tied to that Steam account so you can't trade or sell them on the Steam Market. Existing keys are not affected but they will eventually run out of course. The question is, why? Well, according to Valve "worldwide fraud networks have recently shifted to using CS:GO keys to liquidate their gains" and "nearly all key purchases that end up being traded or sold on the marketplace are believed to be fraud-sourced" so they're putting a stop to it.
While this may affect some legitimate users, it's going to be tiny compared to the overall amount that were being sold. This comes not long after adjusting how the loot boxes for French players work and the same changes for buying/selling keys will likely be added into Team Fortress 2 at some point as well.
Additionally, a small patch for CS:GO went out yesterday to fix a UI issue sometimes displaying CS:GO Weapon Case as genuine quality, along with two fixes for Danger Zone: players can no longer avoid damage with an invalid player name and drones cannot grab cargo if they're set to self destruct.
Find CS:GO free on Steam.