WordPress themes go through a review process that is rather stringent. The review is a manual process so somebody actually installs the theme, takes a peek at the source code (usually it is just functions.php to check the function naming conventions), checks for licensing issues and spam links, and gives the theme the O.K. before the theme is listed on the WordPress Theme Directory.
Because it is a manual process, the review of the themes takes a while and the queue of themes awaiting a review is far too great to handle with the regular review process so the theme review team decided to have an online meetup on the IRC channel #wordpress-themes to get themes reviewed. The event did result in at least a dozen themes out of the queue (a rough estimate 2 hours into the event; more volunteers did join in after we came up with the estimate) with volunteers putting more themes into their To-Do list so there is an end in sight to the almost never-ending wait that theme authors have for getting a review.