Every day, the Fortune staff spends hours poring over tech stories, posts, and reviews from all over the Web to keep tabs on the companies that matter. We’ve assembled the day’s most newsworthy bits below.

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  Cisco (CSCO) exec Tony Bates will be Skype’s new CEO, replacing Joshua Silverman, who had filled the position since early 2008. (Reuters)
• Yahoo (YHOO) head of Audience David Ko is leaving to lead Zynga’s mobile efforts. According to sources, Zynga has been after Ko for months. (All Things D)
• Twitter has a new CEO: company COO Dick Costolo. The former Google employee and Feedburner CEO joined the social network in September of 2009 to help lead monetization efforts. The catalyst? Twitter’s recent redesign. (TechCrunch)
• Amazon (AMZN) is purchasing Spanish Internet retailer BuyVip, which offers discounted overstock from luxury brands like Dolce & Gabbana and Louis Vuitton, for approximately $96.5 million. (The Wall Street Journal)
• Healthcare cloud-based app suite CareCloud, which streamlines the managing of physicians’ businesses and helps them virtually work with other doctors, received $5 million during its second round of funding. (TechCrunch)
• Tesla (TSLA) is recalling 439 of its 2.0 and 2.5 Roadsters after one vehicle experienced a short, smoke and “possible fire.” (VentureBeat)
• Barnes & Noble (BKS) launched its self-publishing portal, PubIt!, giving independent writers another venue to sell their literary works. Ebooks will be available for purchase between 24 and 72 hours after upload and priced between $2.99 and $9.99. (Authors get 65% of the list price.) (Engadget)
• Rumor of the week: Palm’s next webOS-based device, dubbed “Mansion,” could be touchscreen-only and feature an 800 x 480 display. (SlashGear)
• Usually, a product endorsement is a great thing — unless it’s endorsed by a (fictional) serial killer. That’s what happened this week, when TV murderer Dexter made the Nokia N8 his phone of choice during the most recent episode of the popular Showtime series.  (Engadget)
• Facebook is having an event this Wednesday. Possible announcements include: a dedicated iPad app (finally), an expanded version of Places or Credits, or… The Facebook Phone. (TechCrunch)
• Goldman Sachs (GS) recommends Microsoft (MSFT) split off its Xbox business because the gaming division’s potential profits are being hurt by overhead from the overall corporation. (Gamasutra)
• IBM (IBM) released CityOne, a “serious game”  tool aimed at urban planners, civic leaders and execs looking to make cities more environmentally and socially sustainable. Trailer below. (AOL News)

[youtube=http://www.youtube.com/watch?v=kIn-IcR3umQ]