Countries all over the world, dictatorships and democracies alike, have in the last few years sought to tame — or plug entirely — that real-time fire hose of public opinion known as Twitter. But on the sidelines of the General Assembly meeting over the last couple of weeks, ministers, ambassadors and heads of state of all sorts, including those who have tussled with Twitter the company, seized on Twitter the social network to spin and spread their message.

One thing we learned about Twitter this week: its user base is very international and growing more so by the day. That's not an inherent problem; it may indeed be an opportunity as most global ad growth is happening outside the U.S. But this is a problem: Twitter appears to be reaching full penetration in the U.S.

One small "hashtag" fueled by a big dream has spread from the West Coast to the East Coast, inspiring everyone -- kids, parents, even celebrities -- to pack lunchbags for those in need. The idea behind this nationwide grassroots movement, dubbed Hashtag Lunchbag, is quite simple: Gather a group of your friends to pack lunches, pass those lunches out to people living on the streets of your neighborhood, and then document your efforts on Twitter, Facebook, or Instagram to inspire others to do the same.

As Twitter heads toward its high value IPO, the attention is on its revenue and growth numbers. However, a big part of the story is the pervasiveness and influence of the messaging service. Compared with Facebook, with over a billion users, Twitter is a midsize town, with about a quarter of the audience.

On a day when President Obama told delegates at the United Nations that he welcomed the opportunity posed by diplomatic overtures from Iran’s new president, Israeli diplomats in Washington sounded a very different note online, mocking the moderate cleric as scarcely different from his predecessor, Mahmoud Ahmadinejad.

China's recent history has been marked by two key features: rampant economic growth and tight governmental control on the spread of information. Now, it seems, both are starting to wane, as economic expansion is slowing down and even the government's zealous grip on the internet is beginning to loosen.

For a sitting head of state, Toomas Hendrik Ilves spends an awful lot of time on the internet. Most world leaders leave their online presence to aides, punctuated only by the occasional initialized platitude. The president of Estonia, however, spends hours a day reading, writing, and tweeting to his nearly 17,000 followers about issues ranging from European Union border controls to the latest Thomas Pynchon novel.

The Prime Minister's official Twitter account has marked a highly offensive tweet as a "favourite" on the social networking site. The tweet, from a user mocking former Tory chairman Lord Tebbit, was posted in response to the Prime Minister's message of condolence for victims of the Nairobi terror attack.