There’s no question that the Google-Firefox browser partnership has been a boon to both parties. Google ships as the default search engine in the Firefox search box and as the default start page when the browser loads. That kind of distribution has to rank up there with Internet Explorer shipping with every PC. And the Mozilla Foundation has benefitted too, reaping untold millions from Google as part of the deal.

So the news that Yahoo has nailed the same kind of agreement with Firefox in China, Japan, Korea and Taiwan could be a big deal. We don’t know what kind of usage Firefox has in those countries. But it would be a fascinating social experiment to see how many people actually use Yahoo Search instead of Google just because Yahoo’s the default the search engine.

“This is obviously really important to us,” Yahoo’s Gaude Paez told us.

Yahoo will pay Mozilla based on the number of searches that come through Firefox.

We wonder what kind of competition there was for this deal. It’s hard to imagine Google would lose this partnership without a fight. And if there was competition between Yahoo and Google, that could only be good financially for Mozilla.

UPDATE: We’re told there was competition.