I am having Samba 3.0.6 and man nmbd contains this: "This man page is correct for version 3.0 of the Samba suite.". I think it should read 3.0.x instead of 3.0, because 3.0.6 version is not 3.0 (however, 3.0.6 is 3.0.x).
3.0.6 is part of the Samba 3.0 series.