Interesting speculation in the closing paragraphs of this article:
Frankly, the most powerful opponent Google might face would be a combination of a portal and search engine with one of the big social networks. A year from now, if the players were MySpace-Yahoo and MSN-Facebook, Google might be sweating a little more.
How will Google respond? It certainly has shown an interest in influencing the arrangement of its rivals. But this year, no matter how much it studies Machiavelli, it may need to actually buy a company to keep it out of the hand of a competitor.