See article on BBC online from Julian Smith, senior analyst at Jupiter Research. Noteworthy quote:
"When a company's marketing story differs from the one being told by online consumers, a credibility gap will emerge that could have dire consequences on brand perception and favourability. "
Biggest task is alignment then but that often goes way beyond PR agencies remit...
BTW, I just came back from a fantastic social media event organised by my colleagues and friends at Digital PR in Milan. More on that Monday when I'll have more time to blog (study, study...)