It works!!! I finally found the trick. Really interesting, I have no idea why I need to do that now. Could interest cptvitamin too.
I used to be able to mount samba shares on jaunty by doing
which doesn't work anymore on karmic.
sudo mount //netbiosname/sharename mount_point -o username=myname,password=mypsswd
But I get it to work by doing
where workgroupname is shore.mbari.org in my case (to give an example)
sudo mount //netbiosname.workgroupname/sharename mount_point -o username=myname,password=mypsswd
ie. I have to type the whole adress of netbiosname. Which is weird because I can ping netbiosname (without having the enter the whole adress) and I specified workgroupname as the workgoup in smb.conf.
Hope that will help others
edit: I had to do a fresh re-install because of another problem. And this time I could mount netbiosname directly without having to specify workgroupname. So my problem was related to something that went wrong during the upgrade...