The Google Blog says that "over the past four years, Google has billed advertisers in 65 countries more than $11.2 billion in 48 currencies, and made payments to advertising partners of more than $3.9 billion. "

While the margins are what the financial analysts focus on, I'm more impressed by the geographic reach: 65 countries. While the revenues from many of these countries is just a sliver of the total pie, Google has done a nice job of seeding these markets.