Yahoo! (NASDAQ: YHOO) has acquired Stamped, a mobile start-up geared toward social recommendations. The service has a smartphone app that allows users to recommend things like books, movies, music, restaurants, and more by giving them a stamp of approval. No financial details were disclosed.

However, The Wall Street Journal reported that a "person familiar with the matter" said the deal was in the $10 million price range. The deal is the first acquisition since ex-Google (NASDAQ:GOOGL) exec Marissa Mayer became Yahoo!'s CEO, and shows that she's serious about expanding the search company's mobile strategy. Robby Stein, one of Stamped's co-founders, was a colleague of Mayer's while the two worked at Google. In fact, most of Stamped's nine employees worked at Google.

On its website, Stamped said it will be discontinuing the current Stamped product by year's end, but will allow users to take their "stamps" with them. The team will be working on a brand-new product for Yahoo!, without elaborating beyond that it would be "big, mobile, and new."

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