Apple has posted Software updates for the iMac and for the MacBook Pro.

1.2 for Tiger (13.3MB) [1] or 1.3 for Leopard (21.6MB) [2]

This update provides important bug fixes and is recommended for 20-inch and 24-inch iMac models with 2.0, 2.4, or 2.8GHz processors.

For further information on this Update, please visit this website: http://www.info.apple.com/kbnum/n306707

MacBook Pro Software Update 1.2 - 14.4MB [3]

This update improves graphics stability and is recommended for all 2.2/2.4GHz MacBook Pro Models.

For further information on this Update, please visit this website: http://www.info.apple.com/kbnum/n306708

Both updates are available either through the Software Update utility or through Apple's support web site [4].