Civilization V has been out nearly two years now and is still going strong. Besides the upcoming Gods & Kings expansion, Steam Workshop support is also on the horizon.
Steam Workshop debuted with Skyrim and since then seems to have served the modding community well, offering an easy way to browse, install, track, and rate mods for a few titles. In the case of Civilization V, developer Firaxis will be ditching the in-game mod browser, and of course will offer the option to subscribe to mods through Workshop., plus support for collections, and more.
The new functionality will launch sometime after Gods & Kings, which is set for June 19.