Apple releases a firmware update to fix a screen flickering issue with 27-inch iMacs.
The new 27-inch iMacs have been giving Apple more headaches that most releases. First there were reports of units being shipped with cracked screens, then performance issues relating to Flash, and then screen flickering problems. The Flash issues was resolved a little while ago with the release of Mac OS X 10.6.2, and this latest firmware update should cure the screen flicker problem.
About 27-inch iMac Graphics Firmware Update 1.0
Updates the graphics firmware on ATI Radeon HD 4670 and 4850 graphics cards to address issues that may cause image corruption or display flickering.
Download here, more information here.
[UPDATE: So far readers are giving this update mixed reviews. Some tell me it's fixed their problems, other say not.]