In the beginning of this year, in an online Journalism blog, Paul Bradshaw spoke of the key features of user generated content online that make it qualitively different from audience involvement in news production in the past.
There is a long history of audience involvement in news production, from letters to the editor to radio and TV phone-ins.
Unlike print and broadcast, on the web users do not need to send something to the mainstream media for it to be distributed to an audience.... a member of the public can upload a video to YouTube with the potential to reach millions. Indeed one of the challenges for media organizations is to find a way to tap into blog programs and photo sharing websites
The second key difference with user generated content online is that there are no limitations on the space that it can occupy. On the multimedia side, Sky and BBC provide online galleries where users can upload hundreds of photos and videos.
The term "user generated content" itself is perhaps too general a term to be particularly useful to jounalists. The most accurate definition might simple be that user generated content is "material your organization has not commissioned and paid for".