What is Geeklog 2?
From GeeklogWiki
Geeklog 2 (GL2) is a kernel that provides application services to modules that run within its environment. This is the successor to the Geeklog 1.x codebase.
GL2 is a complete rewrite which was deemed necessary to overcome design contraints of Geeklog 1.x that prevent Geeklog from being customized to the degree that its growing userbase demands. Geeklog 2 is still in its infancy and provides a tremendous opportunity for others to get involved in cutting edge PHP development.
For the current state of GL2, also see this forum post by Tony.