imac firmware

I have a Flat Panel iMac (M8672LL/B, 15"). I'm running 10.3.9. It is using a modern day SMC wireless device in the USB port (no airport).

I just came across an archived email on my flash drive that talked about G4 power macs which had a 'recent' firmware release. That got me to wondering if my rig was a candidate for firmware updates.

Anyone know about this firmware stuff?