When unmerging a samba version while it is "down", then pid files don't exist so the /var/run/samba directory gets deleted. Then, the next emerge samba (of another version) will not recreate the directory, so samba will fail on startup.
samba-3.0.4-r1 (the only one I tested) works well on this. Which version are you talking about?
It was the latest samba that wasn't in ~x86 yesterday, I think samba-3.0.2a-r2.
i tried samba-3.0.2a-r2 also. No problem with that.
please reopen if there are news
I had this problem when upgrading to 3.0.5. I don't have the rights to reopen the bug, though.
Reopened after Giovanni's confirmation
samba-3.0.5-r1 in cvs. Dir installation rewritten. See bug #58090 for the changes. i.e.: libs location slightly changed, compiler flags extra checks