(FORTUNE Magazine) – It isn't easy becoming a great place to do business, but once a city cracks the list, chances are it will stay there. Of this year's 15 best international cities, nine also ranked last year; the rest barely missed the cut. Why? Because this is not, say, the Academy Awards, in which totally new products are judged each year. The kinds of things that make London, Hong Kong, and Buenos Aires (this year's regional winners) good places to do business--skilled work forces, stable governance, and good quality of life--don't change overnight. That's bad news for St. Petersburg, Russia, and Istanbul in Europe; Managua, Nicaragua, and Havana in Latin America; and New Delhi and Ho Chi Minh City in Asia, which were at the bottom of the pack; they clearly have a lot of work ahead of them. (Are you listening, Fidel?) But it also means that newcomers like Dublin and San Juan, Puerto Rico, have established a positive momentum they should be able to continue.

How does FORTUNE come up with the list? We work with Arthur Andersen, which ranks 85 cities (35 in Europe, 25 each in Asia and Latin America) in four categories--work force, business environment, quality of life for attracting talent, and cost of doing business. Finally, Andersen sends surveys to executives in 160 cities.

One interesting nugget embedded in this mother lode of information has to do with the Internet. Four of the top five cities in Asia also featured among the top five in terms of Internet connections. (Taipei, which did not make the final five, beat out Tokyo, which did.) In Latin America the overlap between Internet connections and ranking was total--although Buenos Aires, the most wired city, still could boast only three connections per 1,000 people, compared with 66 in Hong Kong (Asia's most connected) and 117 for Helsinki, Finland.

Does this mean that the Internet is the key to success? No, not quite. What it means is that the places that have managed to get connected--with all that implies in terms of telecommunications, infrastructure, regulatory capacity, and literacy--are the kinds of places business can get done.

Second, the productivity gap between the rich and not-so-rich worlds remains striking. In Europe, Oslo reported the highest labor productivity per person, $68,056; Dublin was the most productive among the top five cities, at $61,137. In Latin America, Buenos Aires came out on top, but generated only $34,037 a person. For many countries, playing catch-up is still the name of the game.

--Cait Murphy