Apple today released iMac Software Update 1.0 which provides important bug fixes and is recommended for 20-inch and 24-inch iMac models with 2.0, 2.4, or 2.8GHz processors.
System Requirements:
• Mac OS X 10.4.10
• iMac (Mid 2007)
iMac Software Update 1.0 is available via Software Update and also as a standalone installer.
More info and download link (5.1MB) here.