Rotated windows are a nice toy, but I'm really hoping for something to (hopefully seamlessly) replace X once and for all. This project seems to be coming along very slowly, unfortunately. Linux needs the equivalent of BeOS's "App_Server" - a very simple, functional and fast GUI, instead of the layer-upon-layer-upon-layer setup that we use at the moment. Just take a gander at how fonts are handled in X at the moment: Type 1 + TrueType * (Font server or X) * Xft * GUI toolkit. And even then the results are often appauling.
Yeah, and they use Roundup, so they rock :)