Yahoo! has launched its oneSearch mobile search platform for mobile web browsers, taking its new search marketing service to a greatly expanded number of handset users.

Previously, oneSearch, which delivers enhanced results and listings for the small screen, was only available in Yahoo!’s downloadable Go 2.0 application, launched in January. Results pages display search-related ads and sponsored banners.

Yahoo! last night announced it was making the feature available to mobile browsers at m.yahoo.com and would automatically customise the experience to the plethora of different handset and mobile operating systems.

The portal is aggressively targeting the mobile search space, at the same time is courting large advertisers for its desktop and handset search marketing services. Mobile searchers can click through to a landing page or mobile website

oneSearch makes Yahoo!’s mobile ad offering more attractive to marketers by greatly multiplying the number of potential eyeballs for advertisements.

The platform aims to make searches more relevant, friendlier and quicker for on-the-move handset users.

Meanwhile, Medio Systems announced its launch of a new pay-per-click mobile advertising network, MobileNow. The platform will be delivered to the company’s network partners as well as to other parties, and operates using an auction system.

The platform will integrate pay-per-call advertising technology from Ingenio that allows users to click from search results to call a vendor and only charges marketers for calls placed.