Prolific GNOME contributor Jasper St. Pierre has landed new tiling code into the Mutter window manager / compositor. This new tiling code is fully rewritten and based around constrained edges rather than tiling states. The new mode allows for one free-floating edge that can be resized and this new code also supports corner tiling.
To learn more see this Git commit and the associated bug report tracking the feature. This rewritten tiling code for Mutter has been in the works since last summer.