In September, Facebook (FB) purchased popular photo-sharing service Instagram. Twitter, Facebook's biggest rival in the social space, responded by disabling a feature allowing Instagram users to import their Twitter contacts into the service. This month, Facebook and Instagram fired back by preventing Instagram photos from displaying within Tweets. Twitter founder Biz Stone responded with a snarky tweet directed at Instagram CEO Kevin Systrom.
Consumer Impact: The impact on users is fairly minimal, and if you don't use either service, you might not even understand what that last paragraph even means. In a nutshell, it makes it harder to share friends between the two popular services, and also makes it slightly more difficult for your friends to see the pictures you tweet using Instagram.
Compared with a lockout of an entire sports league or the disappearance of your favorite shows, that's a relatively small burden on consumers. But it's a good example of how even normal competition can make consumers' lives difficult. As The Economist points out, both services have a vested interest in keeping users on their respective sites as long as possible, and both moves certainly help in that regard. It's just unfortunate that this means making each service more closed off for users who would prefer to have a seamless social networking experience.