Ben Silbermann, CEO, Pinterest RoadMap 2012 (c) 2012 Pinar Ozger pinar@pinarozger.com

Nook representatives noted in the press release that Pinterest had been one of the most-requested apps for the Nook store, which allows customers to download games and social apps. Pinterest also fits with some other features of the new tablets Barnes & Noble introduced last fall: An improved magazine- and catalog-reading experience, and a “rip out the page” feature that lets users save pages from catalogs and magazines to a digital scrapbook.

Pinterest, long known for its innovative design, has been growing rapidly over the past few years, and just took in $200 million in a new round of financing  that puts that company’s valuation at $2.5 billion. A February Pew report estimated that about 15 percent of online adults use Pinterest, and the company has been stepping up efforts to provide businesses with analytics tools and specific landing pages just for them. Last week, Bing announced that users would now be able to pin images directly from the search function to Pinterest.

In February Barnes & Noble reported that Nook revenues for the third quarter were down 26 percent to $316 million, even though the company released two new tablets during the year. The company said it expects Nook Media, which it spun off as its own segment last year, to bring in revenues of $2.5 billion for fiscal year 2013.

In a post on Pinterest’s blog, Sciarra writes that he’s been hired as “Entrepreneur-in-Residence” at VC firm Andreessen Horowitz, an investor in Pinterest. With his departure, cofounder Ben Silbermann officially becomes CEO.

Content-sharing invitation-only site Pinterest launched in March 2010 and has grown remarkably fast in recent months, hitting 17.8 million users in February according to comScore. The majority of the site’s users are women aged 25 to 44, many from the South.

In his goodbye post, Sciarra touched on why he thinks Pinterest has been such a success:

[The] best internet services aren’t just ways for people to escape their everyday lives. Instead, those services with longevity — with real “legs — enhance folks’ day-to-day experiences, deepen their relationships, and show them things about themselves they didn’t know before.