It's possible to place an image on the map (version >= 2.10h):

{mosmap imageurl='http://tech.reumer.net/images/powered_by.png' |imagex='1'|imagey='1'|imagexyunits='fraction'
|imageanchorx='255'|imageanchory='108'|imageanchorunits='pixels' |imagewidth='165'|imageheight='68'}