Brad Stone at the NYTimes Bits blog talks about how developers are stretched thin by not having similar APIs or ways to code across platforms. He's talking about social networking, but it's also true for virtual worlds and the related world of multiplayer games, maps applications and all kinds of other platforms. In this most forefront of media environments we have the equivalent of old media thinking: everyone has their proprietary environment, doesn't open up, doesn't allow users or developers to move across and around platforms seamlessly. Sure there's the Open ID movement. We could probably also use the open developer movement, the open avatar movement, the open social network movement.
This probably goes against classical business reasoning of trying to gain unduplicable business advantage. But the multiplicative effect for those who participate might give them more of a business advantage than the walls do, ultimately.