Minor, but it caught me out, so it seems worth fixing before release if possible:

Summary: (a) need to remove -P parameter from existing smb printing scripts
(including the examples distributed with Samba 3)
         (b) add description of new -P smbclient parameter to man page?

Description:
The smbprint example scripts in 'samba-3.0.0rc4/examples/printing' all use the
-P parameter with smbclient. In previous versions of Samba, the meaning of this
parameter was 'connect to service as a printer'. However, in version 3, a
non-backwards-compatible change reassigns the meaning of this parameter to
'machine password' (seems to be undocumented in the man page?). When upgrading
from 2.2.8a, I found my own existing printing scripts no longer worked, issuing
the mysterious message 'ERROR: Unable to fetch machine password'. I was printing
to a Win9X print server which has no machine password!

However, smbclient -h documents the new description of the parameter, and I was
able to find an old version of Samba from which I could query the previous meaning.

Solution:
Removing -P parameter corrects the problem and allows the printing scripts to
work again