Most people here seem to be suggesting that you can get the "idea" of something from a game, but not the execution. It really depends on what we're talking about. There are valuable people skills you can learn from games. This to me seems like the biggest thing games teach.
There are creative/design skills (either built into the game, like minecraft, or as a result of games, like garrys mod machinima short films, or level/mod tools for games. Puzzle games I suppose give you cognitive training, but we're slipping back into concepts here. For the very young (although not sure how relevant this is today) learning to read, and getting used to reading was a part of games. For me personally, Final Fantasy VII was a gateway into books. =D These are all very specialised though.
So lets go back a bit... Games can teach you people skills?! "But Sneak Lemming - I thought that gamers were socially inept nerds and geeks? " I head you say.
"Ahh" I reply "That is simply your mind being convinced by stereotypical media."
The first and arguably most important skill that games can teach you, is how to be a member of a team. Today so many jobs are based around teams - and being able to communicate and be active in a team is a life skill. From basic team games, and complex co-op games, to MMOs, working with others is usually a key part of good gameplay.
With being in a team is the ability to communicate. In order to progress in any real fashion in team games, communication is a must - and all but the most basic co-op games will require communication. MMOs are certainly no exception. Even if you don't end up working in a team you will have to communicate in some way what you are doing.
Written skills are practices in games all the time, from taunts in counterstrike, to angry forum posts on Blizzards forum criticizing their 10 page technical document of patch notes. You see where I'm going with this. Alright, not strictly games - but it's not something you see people do when watching TV Soaps...
Management and Leadership skills. This is the most nuanced of the "people" skills that games help people with, mainly because it's not very common for console gamers, which are the majority. This is normally seen around either MMOs or competitive FPS games that have team-based tournaments. In MMOs all guilds are run by people - the big ones have to be managed with a hierarchy, and they also need leadership. For the counterstike teams who compete in the CAL tournament (or w/e its called now) they need team leaders, people to organise training sessions etc.
Games won't teach you how to shoot, or how to fly a plane, but they have alot to give in the way of social skills.
Best part? You probably don't even realise that Portal 2 is making you a better person. That is the genius of games.