It looks like Valve is following the example set by websites like GameFAQs with a new Game Guides section on Steam. The feature, currently in beta, allows Steam users to share text, images, and embedded videos designed to offer tips and tricks for the various games available through the digital storefront.
The content offering is pretty light right now, as you might expect for such a new feature. That said, with the ability to call up a Steam overlay from inside of any game, there's a lot of potential here for quicker access to the help you might be looking for. Especially when it comes to games that aren't as friendly to tabbing out.