Pode's SVG plugin is cool, but yeah, it isn't quite up to the job. There is also a polygon plugin that give you vector shapes, but also has some limitations... you only really get scalable shapes if you make sure you don't give them outlines... (outlines apparently get rendered as a texture or something, so scaling causes pixellation) so it can only really be used for simple solid shapes with flat colours... among other problems.
Anyway, since it is apparently possible to swap your PNG files for SVG files after exporting, then surely it can't be too much trouble to incorporate official support somehow. Would like to hear what Ashley thinks about it, in terms of how realistic a request this is.