WordPress users dominate 8.5% of the web. This stat was made made public by CMSWIRE.com in article on September 2010. My prediction is that this number will continue to climb since WordPress is a top 20 website, which hangs around other elite company like Google, Yahoo, Facebook and MySpace. Now that WordPress has partnered with Microsoft, users can now publish posts from Windows Live. WordPress also has apps for Android and other devices so users can create and publish content.
However, the numbers can be misleading because WordPress hosts free blogs and many people jump on the free bandwagon, then get hesitant to pay for a real website and hosting.
Although I like WordPress and its simplicity, I still think Joomla and a paid blog is a better option since it has great seo, styling, and comment controls. All in all, a seasoned WordPress programmer and a seasoned WordPress expert could spice a blog quite nicely with specific user rights and comment controls.