Latest Steam Beta introduces community-created multimedia game guides.
Keying into a big reason why users alt+tab out of Steam, that being in order to check a guide for a tricky tidbit of game-specific information, Steam is introducing a Guides section for each game's store page.
Unlike the long-standing player's guides that have been available for sale on Steam, the new "Guides" tab (located within each title's "Game Hub") is fueled by the community, and is capable of hosting more than just text.
This new feature may encroach on established game-guide repositories like GameFAQs, but it seems on the surface to be a way to keep users in Steam, and to encourage the Steam community.
Source: Steam News