“I clearly knew that I had to do something, and I failed to do it … A CEO should take responsibility. I screwed up.” — Chairman Eric Schmidt on the company’s struggle with social. (All Things D)

* During his appearance at All Things D’s D9 conference last night, former Google CEO and current chairman Eric Schmidt covered a number of topics including the company’s attempts at integrating social elements into its services, the fastest-growing technology companies — Amazon, Apple, Facebook, and of course, Google — which he dubbed the “Gang of Four,” and even that age-old technology argument: Macs versus PCs. When it comes to security, “you could use a Mac instead of a PC,” he said, arguing that viruses are less likely to affect Mac users. He also recommended pairing that Mac with Google’s Chrome Browser and Gmail’s two-step authentication feature. (The Next Web)

* Apple’s planning a blitzkrieg of announcements at this year’s Worldwide Developer’s Conference (WWDC) on Monday, including the proper unveiling of its iOS 5 mobile operating system and Lion desktop software update, as well as its much-speculated about iCloud cloud-based music service, most of which will likely be discussed by Steve Jobs himself. (This is my next)

* The unofficial tally of global Facebook users is approaching 700 million. (SocialBakers)

* How the social Web can go beyond Facebook… (All Things D)

* VMware acquired social communications platform Socialcast, which mashes up corporate activity streams with features like Outlook and SharePoint integration, for an undisclosed amount. (TechCrunch)

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Zynga’s latest probable blockbuster, Empires & Allies, launches today in 12 languages. The combat strategy game encourages users to build up its island-nation empire, recruit friends, and divide and conquer through battles, building, and bargaining. (Zynga)

* Inside the growing — and very lucrative — world of virtual currency. (AdWeek)

* Better whip out those bluetooth headsets… According to the World Health Organization (WHO), cell phone radiation really may cause cancer. As a result, the agency now lists mobile phone use in the same “carcinogenic hazard” category as lead, engine exhaust and chloroform. (CNN)

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