Robert Scoble, the maverick standard-bearer of corporate bloggers, has left Microsoft to join a Silicon Valley start-up.

Mr Scoble is to start working for PodTech.net, a company that plans to broadcast interviews with technology industry leaders over the web.

"I am jumping into Podcasting and Videoblogging … with both feet," he said on his influential blog of his decision to leave the world’s largest software developer.

"I love Microsoft and Microsoft did not lose me - at least as a supporter and friend," he added. "It is the best big company in the world."

However, his departure is likely to be been as a blow to the group, which has struggled with public image problems, especially as bloggers have become increasingly vocal and influential.

It comes as Microsoft steels itself to battle with rivals Google and Yahoo! in the fiercely competitive market for internet-driven services.

Mr Scoble had garnered a massive amount of attention within the IT industry after he chose to go off-message to criticise Microsoft on topics such as its controversial entry into China.

Inside Microsoft, he was a driving force behind Channel 9, Microsoft’s corporate blog.

"Robert did more in his three years at Microsoft to improve the corporate image than anyone I know," said Don Dodge, another Microsoft blogger.

"In his own unique way he put a friendly, honest, and responsive face on Microsoft."

Fittingly, news of Mr Scoble’s move was broken by Silicon Valley Watcher, a blog run by Tom Foremski, a former Financial Times reporter.

"Mr Scoble has expressed frustration working at Microsoft and he has also been unhappy with his compensation," he said.

"He has created a tremendous amount of positive publicity for Microsoft but there have been many within the organisation that have resented his very public position."

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