Want to find out how many people are running the latest version of WordPress? It might surprise you to know that it’s currently only 4.3% of all WordPress users. There’s quite a hefty chunk of users stuck at version 3.0 and they’re missing out on tons of new, exciting features. You can find all that information and more on the WordPress Statistics page.
Additionally, you can also view a graph showing what version of MySQL is most in use by sites currently running WordPress: