The latest Technorati State of the Blogosphere report shows that 39% of all blog postings are in english. Japanese is the second-most popular language, at 31% and China third with 12%. Here's Technorati's pie graph for June '06:
Dave Sifry notes that there are some significant underreporting issues, especially in Korean and in French. For example the largest Korean blog and hompy services (like Cyworld or Planet Weblog) are not being indexed by Technorati. I'm also wondering why Chinese language is only 12%, when it was at 25% in Nov 05 according to Technorati. There's another note in a previous report that many Japanese blog posts may be coming from mobile phones, hence their high percentage.
In general there could be any number of holes in Technorati's analysis, but it's the best stats we've got so far on international blogging.
The one trend I'm sure of is that english is just one part of the blogosphere - and of web apps and sites in general. This is why I'm enjoying doing my series on International Web 2.0 markets, as it gives us some context on what is happening in the real world. Silicon Valley is where the fun action is at, but there's a whole world happening outside of it!