Stream of posts with thumbnails in the middle column? Vertically stacked stream filters on the left column? We love the structural layout of Facebook's upcoming homepage, and this is why...

December 8th, 2008: Sketch of Koprol layout

February 6th, 2009: Launch of Koprol private beta

Screenshot taken by Media-Ide, annotation added by us

March 4th, 2009: announcement of Facebook's future homepage