How things can change in the space of a year ... back then, this hint gave a NetInfo workaround for changing the default shell in OS X. Thanks to last month's Macworld (the Geek Factor column, page 88), we now have an easier, older way: the chsh command.
chsh -s /bin/bash username
will permanently change the default shell for the named user.
Mac OS X Hints
http://hints.macworld.com/article.php?story=20040223163911891