If you want to be our little test bunny when it comes to samba and smbup, I will gladly help :)
I have not managed to get an hold of an 10.8 mac yet, so have not been able to test it out myself.
EDIT: I actually found an in-depth guide on this for 10.7, if youre willing to try this on 10.8 it would contribute a lot :) LINK
There seems to be a major misunderstanding between OSX 10.8 desktop and server. Does anyone know how to set up the server side. We are using Mountain Lion Server which uses runs services and not the normal System Preferences settings. The server overrides all SysPref settings. SMB is an option, but Samba is not. Installing Samba will not work with the server settings as far as I can see.
It is possible to install SMBUp on the OS X 10.8 Server.
If samba works after that, I do not know cause I have not been able to try it out myself.
I'm going to look into that SMB HowTO you linked!