Information from Software Update.
This update fixes several issues to improve the stability of iMac computers.
After the firmware is successfully applied to your Mac, your Boot ROM Version will be:
IM71.007A.B03
You can confirm the version of the BootROM installed on your computer using System Profiler.
For further information on this Update, visit http://docs.info.apple.com/article.html?artnum=303364.