How many posts are there on blogs as opposed to message boards?

How many posts are there in the blogosphere and boardscape? Here are some napkin estimates I've made based on the latest State of the Blogosphere (now called State of the Live Web) from Technorati's Dave Sifry and some statistics from BoardTracker.

According to Dave, there are some 230 million posts that use tags. This accounts for 35% of all posts, which leads one to a figure of 657 million posts on the blogosphere (at least those that Technorati tracks). However, this does not include comments.

BoardTracker, the largest message board search engine, estimate that there are over 3 billion discussions and about 50 billion posts on message boards. A discussion “thread” has on average 16 replies.

Accounting for comments in blogs (and I am unaware of any average figures for comments on blog posts as opposed to message board threads), this could bring the number of blog discussion entries (starter posts and comments) to about 10 billion posts and comments.

So the boardscape is roughly 4.5 to 5 times bigger than the blogosphere. Of course message boards have been around for longer than blogs, but they are interesting figures nonetheless...