CustomPress is a great plugin, it already covers what one would expect from it, but adding just this tiny little feature would be the icing on the cake.
When creating the custom type there's a field, at the bottom of the setting page, to add the icon which will be used in the dashboard. Great work, and just in case you need an icon for that, try using this library of icons, you'll find almost every possible icon there.
But I missed having an option to also change the 32x32 pixels icon showed when you the custom post type editing page. You can fix that with just a few extra lines of code, but I think this is such an easy feature to add to the plugin and it would benefit the whole community.
If you would like to see this feature too, please add a comment below, thanks!