I would KILL for something like this on Android. I know on Android it's not standard to layout UI in code but even just a better Android WYSIWYG layout xml designer would be wonderful. People have proven that it's possible to create gorgeous custom Android apps but it's definitely easier on iOS.
It looks like you can create vector-based custom controls and export them as Obj-C code. Custom controls are a real pain to layout on Android, so this would be great.