Here is a image of it in action:
http://www.pasteall.org/pic/show.php?id=6351
What it monitors:
* VRAM used by textures created via bf_gpu and BL_Textures
What it does not monitor:
* VRAM used by the Blender ui
* VRAM used by 2d filters
* VRAM allocated by the user via KX_Scene.pre_draw and KX_Scene.pre_draw