In fact, we may be #1! That's according to Professor Leonard Waverman's Connectivity Scorecard, which rates a country's wired-ness by looking at a wide range of different factors, not just speed and adoption rates.
Because, as we know, we're getting trounced there. Japan's fiber connections blow away even the speediest FiOS install you can get here, and South Korea's percentage of homes with broadband connections makes our (albeit significantly less population-dense) country look almost third world.
Waverman's Conectivity Scorecard, besides providing a great Flash interface to scroll through each country's ratings, takes into account not just pure infrastructure statistics, favoring a broader look at how broadband is actually used in three main areas: at home, in businesses and by the government. And while our domestic broadband percentage may be lagging (especially in rural areas), our disproportionately high usage of the high-speed web at work and, if you can believe it, the government is enough to push us to number one.