According to this page:
Apple Security Update 2007-005 updates the following components:
bind
CarbonCore
CoreGraphics
crontabs
fetchmail
file
iChat
mDNSResponder
PPP
ruby
screen
texinfo
VPN

Time for updates.  This is especially critical for the mDNSResponder update!

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Joel Esler
http://handlers.sans.org/jesler