Source : AppleApple has released a graphics firmware update for the previous iMacs running 10.5.2 and above (n.b. official latest release currently is 10.5.2).
We believe that it is safe to assume that the latest iMacs come with this firmware update.
This update is for iMac computers with an ATI Radeon HD 2600 Pro or ATI Radeon HD 2400 XT graphics card installed, running Mac OS X 10.5.2 or later.
It updates the ATI Radeon HD 2600 Pro or ATI Radeon HD 2400 XT graphics card firmware in the iMac to improve system stability.
