If You want Your custom content types to be displayed with an own icon in the SMI, You must register this icon in the script '/silva/service_view_registry/edit/render_icon' (The SMI does not use the same images the ZMI recognizes.) First You should upload Your icon as a '16x16' pixel sized image via the ZMI. I recommend to put it in a 'locals' folder in the Silva root.

Note that this tip is outdated for Silva0.8.6

There is actually an issue to repair this at http://issues.infrae.com/silva/issue87 Add a link in the 'dict' variable in the script; e.g. to register the image '/silva/locals/news.jpg' for a content type with name "My Silva News":

dict = { 'Silva Root' : 'silva.gif',
         'Silva Publication' : 'silvapublication.gif',
...
       	 'My Silva News' : '../locals/news.jpg',   
...
}

The ".." is needed, as the image is taken relatively to the 'globals' folder (alternatively You could fix the rendering of the '<img>' below, of course.)