[R-sig-Geo] shapefiles, images, iimagemaps, and removing internal boundary lines

[matt.pettis at thomson.com]

I have sucessfully inputted a shapefile into a SpatialPolygonsDataFrame object.  I would like to output this file as a .gif/.png/.bmp/.jpeg image and generate an imagemap for the outputted image.  Does anybody know the best way to approach this?
 
secondly (and i may need to start another thread for this), but is there an easy function to remove the interior lines of aggregated shapes (and generate an imagemap again, etc.)?  For example, If I have a map of the U.S.'s with a polygon for each state, could I remove all internal state boundaries to leave just the national border?
 
thanks,
Matt