Not long ago Second Life was everywhere, with businesses opening branches and bands playing gigs in this virtual world. Today you'd be forgiven for asking if it's still going.

Once upon a time Second Life had a Twitter level of hype. Even those without a cartoon version of themselves couldn't plead ignorance due to blanket coverage in newspapers and magazines.

Second Life is a virtual world started by the US firm Linden Lab in 2003, in which users design an avatar to live their "second life" online.

And everything about this world can be customised for a price - new outfits, drinks in a bar, even a luxury mansion can be bought with Linden dollars.

Mentions of Second Life first crept into the UK media mainstream in early 2006.

A year later, newspapers fell over themselves to cover it, devoting many column inches in their business, technology and lifestyle sections to profiles and trend pieces. By the end of 2007 Second Life had secured more than 600 mentions in UK newspapers and m

Earlier this year I attended a daylong conference in Manhattan devoted to education reform. Called Hacking Education, it was a small, private affair: 40-odd educators, entrepreneurs, scholars, philanthropists and venture capitalists, all engaged in a sprawling six-hour conversation about the future of schools. Twenty years ago, the ideas exchanged in that conversation would have been confined to the minds of the participants. Ten years ago, a transcript might have been published weeks or months later on the Web. Five years ago, a handful of participants might have blogged about their experiences after the fact. (See the top 10 celebrity Twitter feeds.)

But this event was happening in 2009, so trailing behind the real-time, real-world conversation was an equally real-time conversation on Twitter. At the outset of the conference, our hosts announced that anyone who wanted to post live commentary about the event via Twitter should include the word #hackedu in his 140 characters. In the r