I blogged last month about the mobile search deal that was being tied up between T-Mobile USA and Yahoo!. It has officially been announced today.

T-Mobile USA has launched a new mobile portal called web2go, that has a Yahoo! OneSearch searchbox right at the top of the page, according to a screenshot from Venture Beat.

In addition to that, some cell phones that T-Mobile will launch from now will have a shortcut button to Yahoo, except of course Google’s G1.

Users will then be more tempted to visit off-deck sites and mobile site (or regular site) owners should see an increase in their traffic from Yahoo! OneSearch if they’re properly indexed there.

Google will still remain a partner according to T-Mobile.

I wondered if Medio would remain present on T-Mobile’s deck and it seems to be the case, Medio will still provide mobile content search results (games, news, ringtones, etc). Yahoo OneSearch is capable of indexing and ranking mobile content but I guess Medio still has the contract for that type of service.