Apple has issued security updates for Mac OS X 10.5.1, 10.4.11 (PPC), and 10.4.1 (Universal) today. The individual packages affected are listed:
Mac OS X 10.5.1: Core Foundation, CUPS, Flash Player Plug-in, Launch Services, perl, python, Quick Look, ruby, Safari, Samba, Shockwave Plug-in, Spin Tracer
Mac OS X 10.4.11: Address Book, CUPS, ColorSync, Core Foundation, Desktop Services, Flash Player Plug-in, gnutar, iChat, IO Storage Family, Launch Services, Mail, perl, python, ruby, Samba, Safari, Shockwave Plug-in, SMB, Spotlight, tcpdump, XQuery
A detailed breakdown of the security fixes is not yet available available on Apple's site. The updates are recommended for all users.