Last month in February the NY Times wrote an article detailing how blog platforms were some how being canibilized by Facebook and Twitter, with only Tumblr showing healthy signs of growth (at least among the youth).
While no one can dispute the fact that social networks are claiming their fare share of online content (at least upon Twitter and Facebook), their presence has yet to starve blogging as a whole and (not surprisingly) they are often used by bloggers themselves to promote their content.
Other blogging platforms are also boasting healthy signs of growth, with Tumblr approaching 15 million blogs, with smaller players like OnSugar (which is a fork of Drupal 4.7) gaining influence as well.
Note: Although there are probably as many self hosted WordPress blogs as there are WordPress.com blogs, there is currently no way to track them all as not everyone installs WP.com stats or Google Analytics within their blog.
According to Network World’s research (who analyzed the top 1 million sites online), WordPress’s total market share is between 6.9% (according to Quantcast) and 12.9% (according to Alexa), respectively.