<esri:PictureMarkerSymbol id="markerSymbol" source="images/star.png" height="25" width="25"/>
<esri:WeightedClusterer id="clusterer" symbol="{markerSymbol}"/>
Yes, that should work. The cluster would be represented by the star. What's happening when you try this?
It's actually working as expected. The cluster is turned into a single Graphic and it's being drawn using the given symbol. Any other behavior depends on the symbol that is used.
Drew,
Actually it does.
http://thunderheadxpler.blogspot.com/2010/08/image-flare-symbol-for-clustered.html