As Techcrunch indicate in their post (see link above) Facebook will essentially be enabling the web to measure itself. Currently Google famously measures the entire web using machines and formulae with a relatively small amount of human intervention. Facebook will get the web to essentially index and rank itself. There can only be one winner in that fight. Crowds beat machines every time. Perhaps Google will step up and roll buzz out further to combat that Facebook expansion? I can't see another solution...Google may have user reach but Facebook has relationship depth. And the required immense traction to go for it.
If Google don't combat Facebook effectively then the end result could be a brand new search interface from Facebook that brings back results based on LikeRank as opposed to Pagerank. A sort of Yahoo (& Delicious') MyRank come good? That idea was just too early and used the wrong tool but it was the right idea.
Ultimately the reason why only Facebook can win this fight with Google is that no matter how smart the Google algorithm is, there is no substitute for the human mind, the human hive and the viral unpredictable qualities of humanity. As Frank Zappa once said:
The computer can't tell you the emotional story. It can give you the exact mathematical design, but what's missing is the eyebrows.You like?