Social networking start-up Pinterest has rolled out versions of its service for Android-based smartphones and for the iPad, its latest move to boost its appeal to a broader audience. An online scrapbook where users can “pin” images and share them with others, Pinterest has grown to about 23 million users in July from about one million a year ago, according to online analytics firm comScore. In its first official press briefing, Chief Executive Ben Silbermann said on Tuesday the Android app was among the most requested items by users. Read the full story at NBC News.