iMac ATI Radeon HD Graphics Firmware Update 1.0.1

Apple has released a graphics firmware update for the previous iMacs running 10.5.2 and above (n.b. official latest OS update currently at 10.5.2).
Naturally, one assumes that the latest iMacs come with this updated firmware.

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.