The article gives some history and data that covers the basics of a 90-9-1 rule with respect to participation - most people just lurk, some interact occasionally and a few are very active. Many people know this and if you've read Clay Shirky's "Power Laws, Weblogs and Inequality" article you'll be familiar with the idea. Although there have been comments elsewhere that Jakob doesn't "get" RSS (and his alertbox site doesn't have an RSS feed), I think Jakob does understand the implications of RSS and this post provides some value by highlighting some issues and suggesting how to design useful systems in the context of participation inequality.
Search. Search engine results pages (SERP) are mainly sorted based on how many other sites link to each destination. When 0.1% of users do most of the linking, we risk having search relevance get ever more out of whack with what's useful for the remaining 99.9% of users. Search engines need to rely more on behavioral data gathered across samples that better represent users, which is why they are building Internet access services.
Make participation a side effect. Even better, let users participate with zero effort by making their contributions a side effect of something else they're doing. For example, Amazon's "people who bought this book, bought these other books" recommendations are a side effect of people buying books. You don't have to do anything special to have your book preferences entered into the system. Will Hill coined the term read wear for this type of effect: the simple activity of reading (or using) something will "wear" it down and thus leave its marks -- just like a cookbook will automatically fall open to the recipe you prepare the most.
(Bummer - Jakob Nielsen had a 'User Experience 2006' in Seattle a few weeks ago and I missed it...but maybe I can catch some of it on a blog somewhere)
Added: Here is another good article from Jakob Nielsen about traffic log analysis.
The top 10 queries accounted for 10% of the total traffic, so each one of these queries is obviously more important than those that brought only one visitor. Taken together, however, the single-use queries accounted for three times as much traffic as the top 10 queries. This statistic shows the folly of focusing search engine optimization solely on a few high-performing queries. Your site must be found when users enter relevant queries -- and the possibilities are typically vast.