When Microsoft made its deal last month with Yahoo to provide the search infrastructure for its home page, using technology from Bing, it left open and non-exclusive the fate of several deals the one-time #2 search provider had already made, especially with carriers. Specifically, does Bing become the default search provider for services that had previously made a deal with Yahoo? The answer appeared to be no.

Today, that suspicion was roundly confirmed, as one of the world's largest cooperative portals with Yahoo -- one which still bears the Yahoo brand -- quietly but obviously switched its search box to one that was "powered by Google." In a move first discovered by the UK-based blog Connected Internet, BT's Web portal BT Yahoo became a carrier of Google search rather than Bing.

The move marks the apparent beginning of the dismantling of Yahoo-based search engine resources, as the company itself moves over to Bing technology. But that non-exclusive deal apparently does not bind its partners from making the same move. As of this morning, the US' AT&T Yahoo portal page (still known to customers by its previous name, SBC Yahoo) still bears Yahoo's search engine.

The non-exclusive nature of the Microsoft deal could mean that a multitude of lucrative deals Yahoo made last year with mobile carriers, including UK-based Virgin Mobile, may leave an opening for something other than Bing search. Yahoo had re-announced its Yahoo Mobile service last February, at the pinnacle of which was the mobile edition of its oneSearch mobile search platform, with voice search features. Google's mobile search has similar functionality, pointing to the possibility that mobile services as well as PC pages could open unforeseen doors for carriers that haven't seen any lucrative value in Microsoft's presence in mobile in recent months, to perhaps move to Google without disturbing the spirit or even the letter of their Yahoo deals. Mobile carrier deals are where the money is.