I found this by mistake. In the print center, when you press the Option (Alt) key while clicking on the Add Printer button, the first pop-up on the next screen will contain an "Advanced" option. Select Advanced, and you got access to HP JetDirect, SMB and ZeroConf Registered Printers. So no need to add SMB printer through CUPS web interface anymore.
[robg adds: There have been a few hints that included activating this option as part of the process of doing something else, but I couldn't find an actual hint on simply activating Advanced mode ... so here it is!]
Mac OS X Hints
http://hints.macworld.com/article.php?story=20030303232147359