Twitter may charge companies that 'tweet'

The increasingly popular mobile blogging service has revealed the reason behind this month’s PR assault: a plan to charge “brands” for their tweets.

For viral marketers, it looks like the free ride is coming to an end.

In an interview with the UK’s Marketing, pushed today on the magazine’s website, Twitter co-founder Biz Stone says:

'We are noticing more companies using Twitter and individuals following them. We can identify ways to make this experience even more valuable and charge for commercial accounts.'

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