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Facebook founder Mark Zuckerberg has topped the Guardian's annual listing of the 100 most influential people in UK media.

Twitter co-founder Jack Dorsey was placed second, reflecting the growing power of social networking sites.

Their ascent comes at the cost of more traditional technology industry leaders, including Apple's Steve Jobs and Microsoft boss Steve Ballmer.

Experts from the fields of technology, PR and media helped compile the list.

Although social media figures occupied the two top spots, one of the medium's greatest advocates, prominent tweeter Stephen Fry, dropped out of .

Also dumped from the chart was the government's "digital champion" Martha Lane Fox whose job it is to raise public awareness of digital technology, including the internet.

Wikileaks' Julian Assange rose from 58th position in 2010 to 32nd in 2011. His profile was dramatically elevated following the release of leaked US diplomatic cables last November.

Spotify founder Daniel Ek arrived at 40th place, as his music streaming website service launches in the United States.

Steve Jobs was nudged from first place to 5th, but it was Microsoft's Steve Ballmer who experienced the most precipitous fall.

From his 2009 ranking of 5th, he dropped to 29th in 2010 and is out of this year's list entirely.

His exclusion may reflect the fact that Microsoft's only asset which impacts the media directly is MSN news.

Apple, although it does not have such a portal, or any significant social networking presence, exerts huge influence over the music, TV and movie industries and is one of the largest content retailers through its iTunes online store.