[R-sig-Geo] Plot Raster an Shape in one Plot with two different scales

[Marcel Gangwisch]

Hi *,

I want to plot a rasterfile and a shapefile in one plot with two map 
legends.
One scale for my shapes filling the polygon respectively to an attribute.
And one scale for my underlying raster filling the raster respectively 
to the grayscale.

I've already tried it with ggplot2, but I think it's not possible to get 
2 different map legends?

Maybe you have an idea, how to solve my problem.
Or maybe I should make it with QGIS.. but I think the maps made with R, 
look fancier.

Best regards,
Marcel