So I wasn't in the ballroom when the keynote address by Facebook founder Mark Zuckerberg went awry under the less-than-forensic questioning of technology journalist Sarah Lacy.
I didn't see the crowd start to get restless and heckle Zuckerberg about the deeply-unpopular Beacon advertising system, or get a chance to grab the microphone and ask questions when Lacy threw the conversation open to the floor.
And yet I was there in another way, listening to and even interacting with some of my friends in the audience, picking up on the vibe in the room and even tuning in later as Sarah Lacy loudly defended herself.
I was there because I was plugged into Twitter, the instant messaging service that lets users send short text messages to anyone who cares to tune in, online or on their mobile phone.
As I sat at my desk a constant stream of 'tweets', as they are called, was being supplied by many of the people in the room and I was able to reply directly and feel that I too was participating.
One of the reasons for its success is that it is very open, with a clean and well-defined way for programmers to use the service through an application program interface
Of course following short messages on a screen is not the same as being physically there, just as watching a nature show on TV doesn't mean you can claim to have visited the Serengeti.
But the sense of presence that can be achieved is remarkable, especially when you're sitting at your computer working, connected to the internet and with a Twitter client running on your computer so that tweets appear as they are posted. It's rather like reading a novel, where you stop seeing the words on paper and find yourself immersed in a world created for you by the author.
After a certain point Twitter becomes part of the background to life.
A couple of weeks ago I was sitting in the caf of my favourite bookshop with my partner. She was reading about the Habsburgs, Hitler and Weimar while I was writing a talk about the future of publishing.
But I was also engaged in a distributed dialogue with a bunch of friends around the world,
BrightMeadow was cold and complaining, so I sympathised. Luke invited me to look at the first release of his new site, while sambrook was happy to discuss media futures and help me with my talk.
I was there in the cafe but also in this liminal space with everyone else, reading lovemaus's comments on Casablanca, sympathising with technokitten stuck at Madrid airport and wondering whether Jeff went for his run on a chilly New York morning.
Thanks to Twitter I carry my online networks with me as I wander through town, and more and more I see the world through the lens of our shared experience.
Sanjukta is in a cafe in Delhi and here with me; I am wondering what Documentally is filming in Rugby; I know that Yuko42 is lying in bed listening to the Tokyo rain.
Twitter was created by Jack Dorsey while working for San Francisco based podcast company Odeo, and it launched in August 2006, growing by word of mouth until last year's SXSW conference when it emerged from nowhere as the way for attendees to keep track of what was going on and share their thoughts with friends.
One of the reasons for its success is that it is very open, with a clean and well-defined way for programmers to use the service through an application program interface (API).
The developers have gone out of their way to encourage people to write clients for Twitter users, and seem to be both flexible and understanding.
For example clients are limited to 70 requests for data per hour, in order to keep the load on the system manageable and deter spamming.
But they also say 'If you are developing an application that requires more frequent requests please contact us and we'll see what we can do'.
Most of my friends seem to twitter from the web or a client called Twitterific. I prefer Twhirl, which works nicely on my Mac, but thanks to the open API there's a lot of choice.
When I'm out I can even get Twitter on my iPod Touch thanks to Hahlo, which offers a particularly clean and usable interface.
And when I want to follow a particular topic, like SXSW, I use the Tweet Scan website, which searches public updates.
You can choose to keep your tweets private, of course, though there is something about telling the world just what you're up to in 140 characters or less that becomes strangely compelling after a while.
Like many fast-growing services Twitter is far from perfect. The site sometimes creaks and falls over under the load, the interface can be confusing and sometime tweets don't get through.
It is also a dangerous distraction from work, encouraging micro-conversations and followups and witty rejoinders when articles have to be edited, code checked and projects planned.
But as I sit here writing this I feel connected to a community of people, feel that we share a space that none of the social network sites can conjure up, a space that is both here and not here, somewhere between offline and online.
And I feel that I have a foretaste of what tomorrow's network world will bring, when the boundaries have dissolved completely and we can experience the network directly through augmented reality contact lenses or direct neural connections or whatever other technologies make it out of the lab and into the streets in the next decade.
Bill Thompson is an independent journalist and regular commentator on the BBC World Service programme Digital Planet.
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