As already suggested back in April the implementation of the FireWire Target Disk Mode is generic enough to serve any bootable hard disk drive, if you ask it politely using the second script named Set HD to start volume in OF.
To verify this I've dug out my SyQuest removable hard disk drive that hasn't been in use for several years, set it up as target on a Power Mac G4 with an Adaptec 2930 CU Ultra SCSI PCI card and gained full access to it from a Mac Book Pro using FireWire, as if the drive and the notebook (which of course doesn't have any SCSI interface) had been directly connected.
Therefore target-mode should also be able to address drives on SATA PCI controllers, despite any contrary claims often repeated but never challenged.
Trying to access an (ATAPI) optical drive instead of a hard disk failed — all of the CDs and DVDs I've checked out didn't show up on the host, or without their contents. Newer incarnations of the target disk mode offer the hard disk and the optical drive at the same time, as two units. Does somebody know which was the first version (in a Power Mac G4) to implement this ?