Today in Tech: RIM PlayBook, Groupon, Facebook

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  Groupon reportedly turned down Google’s rumored $6 billion buyout offer because its board was concerned about anti-trust scrutiny from regulators. (Google is already knee-deep in two anti-trust investigations.) CEO Andrew Mason also says he wants the company to stay independent in the near future. (Tech Trader Daily and ABC News)

• A group of hackers calling itself simply “Anonymous” claims it attacked Visa’s web site yesterday for suspending payments to WikiLeaks. “Anonymous” was also responsible for taking down MasterCard’s site by way of a denial-of-service attack (DDoS). (CNET)
• Tyler and Cameron Winklevoss (aka the Winklevoss twins), filed another lawsuit against ex-Harvard classmate Mark Zuckerberg, claiming their original $65 million settlement doesn’t fully and accurately represent the booming social network’s current valuation. (Daily Mail)
• Meanwhile, Zuckerberg himself has joined Facebook co-founder Dustin Moskowitz and 14 other American billionaires in agreeing to give away at least half of his wealth. “People wait until late in their career to give back. But why wait when there is so much to be done?” Zuckerberg said in a statement.(NBC Bay Area)
• Did Foursquare turn down a $140 million acquisition offer? CEO Dennis Crowley didn’t deny it when asked at Le Web 10, though he clarified and said that number was a “ballpark” estimate. (TechCrunch)
• Lee Brown, a Yahoo ad sales exec who heads up the company’s ad sales in the New York area, is leaving the Internet company for a position with Groupon. Brown will focus on national accounts this time around. (BoomTown)
• Data organization startup Factual, the latest startup from Google AdSense creator Gil Elbaz, whose company Applied Semantics was acquired by the Internet giant back in 2003, raised $25 million in funding, co-led by Andreesen Horowitz and Index Ventures. (Silicon Alley Insider)
• Android creator Andy Rubin says Google activates some 300,000 phones a day, which surpasses numbers for iPhones, BlackBerries, and Symbian devices. (Coins2Day)
• Best Buy will reportedly one-up RadioShack on December 10 when it offers the 8GB iPhone 3GS for free with a two-year contract. (Previously, RadioShack offered the same iPhone model for $25 plus contract.) (Softpedia Mobile)
• Graeme Devine, the guy in charge of ensuring quality iOS gaming experiences, is leaving Apple to focus on game development for the iPhone and iPad. (Kotaku)
• These days, 8% of all online Americans now use Twitter in some way, shape or form. (PewInternet)
• Psyched for RIM’s 7-inch enterprise-focused slab of joy? Here’s a 10-minute PlayBook demo to tide you over until the tablet hits early next year. (Boy Genius Report)

[YouTube=http://www.youtube.com/watch?v=PYZDl4RNEVE]

Update: According to Facebook Public Policy Manager Andrew Noyes, there is no new litigation between Facebook and the Winklevoss twins. Says Noyes: “The filings referred to in the Daily Mail and other articles are simply the filings by Facebook and the Winklevosses in the Winklevosses’ now two-year old, thus far unsuccessful, attempt to undo their 2008 agreement to settle the parties’ dispute.”