IIDC 1394-based Digital Camera Specification
 

which of the consumer cams support this spec?

Probably none, it is a specification for Digital Cameras in industrial and scientific use. It is supported by the 1394 Trade Association. It is not a consumer spec. What are you trying to do?

I was drawn in by a soft app called Fire-i by Unibrain.

Multi camera support with control over iris shutter speed gain zoom focus etc for EACH camera

It seems ideal for a multi cam shoot but requires IIDC support

I like the idea of a sort of Video Director application running from a notebook via firewire