This layer is definitely a polygon layer, and I can display it as a Dynamic map service. It's a file geodatabase polygon featureclass, being served via an MSD to ArcGIS Server 10. I have a duplicate database running on a laptop, and it's correctly shown as Geometry Type: esriGeometryPolygon
Any idea why it's being listed without a geometry type in this case? I've tried deleting and recreating the service, verified that the featureclass is legitimate, etc.