2 links
Samba Pocket Reference, 2nd Edition
oreilly.com
Covers Samba 2.x and the most important features of 3.0.
Using Samba, 2nd Edition
oreilly.com
Comprehensive guide to Samba administration. This edition covers all versions of Samba from 2.0 to 2.2, including selected features from an alpha version of 3.0.