The two letter domain WP.org was donated to the WordPress Foundation thanks to Syed Balkhi the Founder of WPBeginner.
In a letter on WPBeginner.com Syed wrote:
Over the last year and a half, if you typed in the domain wp.org, then you were redirected to WPBeginner. This was an unexpected and unpleasant surprise for many because you really wanted to visit WordPress.org, home of the popular content management system. Today, I’m pleased to announce that we have donated the domain to the WordPress Foundation.
You can read the full letter here.
It is quite a gesture as WP.org is a valuable domain name and would have plenty of other organizations interested in owning the name.