Yahoo Unveils Mobile Search, Google Rivalry Rages &lt;p&gt;\&lt;/p&gt;&lt;p&gt; SAN FRANCISCO (Reuters) - Internet media company Yahoo Inc.\&lt;YHOO.O&gt; on Wednesday launched its Web search service aimed at\mobile phone users in the United States, opening a new front in\its rivalry with Internet search leader Google Inc. &lt;GOOG.O&gt;&lt;/p&gt;