Panels is a project mainly written in PHP and JAVASCRIPT, it's free.
cvs2git-based port of drupal panels for the d7 port sprint
Welcome to Panels 2.
A little documentation should go here, but Panels 2 is a beast - you're best off checking the online handbook on Drupal.org, or the developer/API docs, which are available at http://doxy.samboyer.org/panels2/