The Twitter co-founder Biz Stone discusses what happened when the site was requested by the US state department to keep running through the Iran protests. And Reddit's Alexis Ohanian talks about the role of the aggregator in news publishing.

While Aleks Krotoski is still off sweating over her PhD, the Tech Weekly presenter baton is handed to Bobbie Johnson in sunny San Francisco, California for a special on-the-road edition of the show.

This week Bobbie meets up with the people behind two of the hottest sites on the web: Twitter co-founder Biz Stone describes what life is like on the hype rollercoaster right now, and then he drops in to the offices of Wired to meet up with the co-founder of social news website Reddit.

It's been impossible to ignore Twitter over the past few months - the site has rocketed in popularity since and now has around 35 million users. As it increasingly plays a role in the way information gets spread around the internet - playing a role in the anti-government protests in Iran, Bobbie Johnson visits Twitter HQ to speak to co-founder Biz Stone.

We also hear from Alexis Ohanian, co-founder of the user-driven news site Reddit.com. It has also become one of the biggest movers of traffic on the web. In 2006 it was bought by Wired, and it remains incredibly popular among hackers and geeks around the world, and Alexis how it got started, and the role of the aggregator in news publishing, as well as how he brought the XKCD cartoons to print.

There's also this week's news on Google's new netbook OS, the 118 800 mobile directory enquiries service, the the media and tech habits of 15 years olds.

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