Now that Yahoo has rebuffed Microsoft’s takeover bid, has Google (with DoubleClick) won the competition to dominate online search and advertising? Eric Schmidt, Google’s chief executive, pronounced himself happy to be crowned, before adding that “as we’ve learned in the electoral cycle, it goes back and forth”.

That implicitly raises the most important question about Google’s dominance. Elected politicians always have a limited shelf-life, whether set by the constitution or by the patience of the electorate. They are also subject to checks and balances while they are in power. Is the same true of Google?