Via a blogpost by Nancy White I found a piece written by Jakob Nielsen about Participation inequality: encouraging more users to contribute .
Jakob Nielsen refers to the famous 90-9-1 rule for large-scale, multi-user online communities that 90% of users are lurkers, 9% contributes and 1% accounts for most contributions. I think that you have to be specific: this rule may apply to public large-scale online interaction. I think the danger of the rule is the people working with smaller (sometimes pass-word) protected online community spaces take the same rule as a guideline and accept this high level of inequality. (which I would not)
The writer talks about 1.1 billion internet users, with only 55 million users (5%) having weblogs according to Technorati. Though I think that's enormous, and produces an overwhelming amount of information, he sees it from the side that blogs participation is very inequal on a world wide scale, with only 0.1% of the blogger posting daily. The problem is that the overall blogposts are not representative of web users. (giving more influence= power to the bloggers). He continues with some tips to enhance participation equality (like making it easier to contribute).
I'd rather look at the use of blogs within a single community of practice. For instance, for our e-collaboration community of practice with about 60 people, I think there are about 8-9 bloggers (plus a group blog) and some people want to start a blog. So the CoP may actually encourage others to start blogging. Unfortunately, it is hard to say how much the blogs influence knowledge sharing and relationship building. I know that it has helped me to know what blogging members are doing and thinking (I subscribed to their blogs). It could be interesting at some point to ask more explicitly how many people in the community of practice read the blogs. And of course it is not imperative that everyone should be blogging. (it sounds a little bit like that's the ideal situation for Jacob Nielsen). To be honest I'm happy that not all 60 have a blog because I wouldn't be able to keep up reading all.
In CPsquare (with about 200 members) roughly 12 (didn't count) people are bloggers and a feed combines all blogposts into a community of practice feed. My concern for this intiative was that people may blog about a wide variety of topics, but I guess in daily life you also talk about a wide range of topics. Again, it would be interesting to know whether it's mainly the bloggers using the feed, the other members, or whether it also works as a boundary tool (open for people outside CPsquare).