It is "Update Time": Security Update 2007-004 v1.1 [updated]

In case you missed it from your software update panel, Apple released the Security Update 2007-004 v1.1.
It is available for PPC and Intel-based Mac, as well as for Mac OS X 10.3.9 client.

Security Update 2007-004 is recommended for all users and improves the security of the following components:
AFP Client
AirPort
CarbonCore
diskdev_cmds
fetchmail
ftpd
gnutar
Help Viewer
HID Family
Installer
Kerberos
Libinfo
Login Window
network_cmds
SMB
System Configuration
URLMount
Video Conference
WebDAV

This update might be necessary due to the previous update of QuickTime.
[update]
Dana, one of our valuable forum members, sent us additional information:

SU 004 v.1.1 is only necessary for those users who have not already installed SU 004.v.1.0. If you have done so, Software Update will not download and install it. On the other hand, Quick Time 7.1.6 is for everybody.