The biggest problem is that Google only had to index HTML; there isn't even an all-encompassing standard for social networks, and if there were, it would quell

The biggest problem is that Google only had to index HTML; there isn't even an all-encompassing standard for social networks, and if there were, it would quell the current rapid development we're seeing. You don't want to freeze something in place before it reaches maturity, and social networks definitely haven't. However, perhaps instead of exposing the data, you could expose the search better. Then, specific standard APIs could be defined concerned with what you want to search for: for example you want to find all the neighboring nodes of a specific node, or during christmas find all people who are friends of sport enthusiasts. This would, however, take the control away from the likes of Google and put it in the hands of the content holders, such as Twitter and Facebook.