Recording industry executives are hoping their landmark deal with search giant Baidu will be the catalyst for commercializing music in China, where rampant piracy has made the world's most populous country an even smaller market than Ireland.

Baidu's Mp3 search users may have already begun to notice that searches for certain songs in the catalogs of major record labels Universal, Sony and Warner are turning up files marked as zheng ban, or "licensed copy, which can be downloaded for free. Thanks to the deal, Baidu users will...