It seems that SAMBA isn't able to show itself as an icon in NN. I encountered a similar problem when trying to do some tests with NT's Server Manager. There I also didn't see an icon. The UNC access works without problems. What kind of problem could it be?
I tried to set in SAMBA and the client a SAMBA 3 WINS server, but this didn't help.
Currently Samba4 does not support NetBIOS browsing. Also see bug #4545 for another browsing technology we should also support.
We do need to bring in the code to implement this.
I've corrected the bug name.
Since it's not really a bug, I'll mark it as a feature request.