According to Watson Wyatt Worldwide's recent study -- 2005/2006 Communication ROI Study -- "Blogs, wikis and discussion boards are being used by firms with high levels of communication effectiveness nearly seven times more than by their less effective peers." (By less effective peers, Watson Wyatt is referring to Intranet with streaming or mpeg video, or streaming or mp3 audio.)
This study of organizational communication goes on to say that "The percentage of companies using these newer tools is still small. However, with 72 percent of companies saying they increased their electonic communications over the last two years, these channels and other emerging technologies could increase in popularity."
Remember, this study is about the effectiveness of employee communication against organization turnover and financial performance. I wonder if the interactive nature of blogs, wikis and discussion boards is beginning to trump the one-directional flow of information that characterizes streaming audio and video as tools for external communication?