If you are interested in KM in general and the application of weblogs as a KM tool specifically, you really need to be reading Jim McGee on a daily basis. One of his recent posts explores knowledge work, weblogs, and fair process. Here is a quote:
As I’ve argued before one of the principal benefits of weblogs is the way that they can make knowledge work more visible. In this context, weblogs serve as a tool that makes fair process a natural byproduct of the work itself. They are a place where explanation can be developed and shared as it is worked out in real time. Moreover, if you can get an institutional environment in which everyone can potentially contribute their perspectives by way of their own weblogs and these perspectives can flow through the system by way of RSS, then you also increase the degree of engagement.
The flip side of this is that without a belief in and commitment to the notion of fair process, weblogs by themselves aren’t likely to last very long inside organizations. While they can be a tool to promote those values, I don’t think they can create those values if they are otherwise absent.
I agree that to successfully deploy weblogs at an enterprise level (across the entire organization) requires an organizational culture that is receptive to knowledge sharing and fair process.
However, I think that weblogs could be used within small islands of an organization that is otherwise not open to this style of knowledge work if given local sponsorship and protection. Over the long term this might lead the rest of the culture in a direction where knowledge sharing could occur more broadly. At a minimum, it would help one section to do their work more effectively. This approach does carry some risks from going against the grain. Use good judgement in how far to push.