Twitter confirmed that it has bought TweetDeck, a popular third-party software application that organizes tweets, the short messages delivered through the online social network. Terms were not disclosed but a source told Reuters earlier this month that a deal for up to $50 million was imminent.

Twitter will seek to notify its users so they can defend themselves before it hands over user information to the authorities, a senior manager said when asked about a privacy dispute in Britain. Users have posted details on Twitter of celebrity scandals, in contravention of so-called super injunctions and could face an unlimited fine and up to two years in prison.

Microsoft announced an update of its Windows phone software, code-named Mango, hoping a host of new features will help it close the gap on smartphone leaders Google and Apple. The update involves 500 new features, including IE 9 as the mobile browser, integrated Twitter and LinkedIn feeds, automated Facebook check-ins, and access to more than 17,000 downloadable applications.

The updated software will appear on new Windows phones beginning this fall, and be available for existing Windows phone users before that, although Microsoft has not set a timetable for making the update available.

Sony will post its third straight annual net loss for the year that ended in March after writing off tax credits in the wake of Japan’s earthquake and tsunami, the latest in a string of grim headlines on the consumer electronics giant. The firm, which previously forecast a net profit of 70 billion yen for 2010/11, surprised markets on Monday by declaring the need to update investors with revised estimates ahead of its official earnings report on Thursday. Sony said it now expected to post a net loss of 260 billion yen ($3.2 billion). The annual net loss would be Sony’s second-largest ever.

IBM surged past old rival Microsoft in market value for the first time since April 1996, marking the latest twist in the fluctuating fortunes of two of the world’s most storied tech companies. Microsoft’s stock has been stagnant since the tech bubble burst in 2000, as investors doubt its ability to move beyond its Windows operating system and Office suite of software. In the meantime, “Big Blue” has refashioned itself as a specialist in business software, servers and consulting, jettisoning its PC business along the way.

Being social,  going local, and paying for the privilege were hot topics on the last day of the Reuters 2011 Global Technology Summit.

Verizon CFO Fran Shammo got testy when Reuters reporter Jim Finkle asked him if he would reconsider charging mobile customers in addition to their data plans to tether their devices:

The third day of the 2011 Reuters Global Technology Summit saw a lot of discussion about the valuation and  potential of “sexy” social networks and lesser known startups.

Saad Khan, Partner at CMEA Capital, talked about investing in LiveOps and Pixazza, two companies the former which he called “unsexy”, and how they “stitch together the world’s labor force.”

Online security was a theme on day two of the 2011 Reuters Global Technology Summit.

Enrique Salem, the CEO of software security maker Symantec, suggested ways consumers can protect their privacy: