>  Is development actively proceeding on the iMac, then?  What is the
>status?

...
obio0 at pci0 dev 16 function 0: addr 0x80800000
interrupt-controller at obio0 offset 0x10 not configured
scsi at obio0 offset 0x10000 not configured
escc-legacy at obio0 offset 0x12000 not configured
zsc0 at obio0 offset 0x13000: irq 15,16
zstty0 at zsc0 channel 0
zstty1 at zsc0 channel 1
davbus at obio0 offset 0x14000 not configured
fdc at obio0 offset 0x15000 not configured
adb0 at obio0 offset 0x16000 irq 18: 0 targets
wdc0 at obio0 offset 0x20000 irq 13
wd0 at wdc0 channel 0 drive 0: <QUANTUM FIREBALL SE4.3A>
wd0: drive supports 16-sector pio transfers, lba addressing
wd0: 4110MB, 14848 cyl, 9 head, 63 sec, 512 bytes/sect x 8418816 sectors
wd0: drive supports PIO mode 4, DMA mode 2, Ultra-DMA mode 2
wdc1 at obio0 offset 0x21000 irq 14
atapibus0 at wdc1 channel 0
cd0 at atapibus0 drive 0: <MATSHITA CR-173, , AD0B> type 5 cdrom removable
cd0: drive supports PIO mode 3, DMA mode 1
bm0 at obio0 offset 0x11000 irq 42,33: address 00:05:02:dd:00:f6
nvram0 at obio0 offset 0x60000
ofb0 at pci0 dev 18 function 0: ATI Technologies product 0x4756
ofb0: 1024 x 768, 8bpp
wsdisplay0 at ofb0: console (std, vt100 emulation)
ohci0 at pci0 dev 20 function 0: Opti RM861HA (rev. 0x10)
ohci0: interrupting at irq 28
ohci0: OHCI version 1.0, legacy support
usb0 at ohci0
uhub0 at usb0
uhub0: Opti OHCI root hub, class 9/0, rev 1.00/1.00, addr 1
uhub0: 2 ports with 2 removable, self powered
uhub1 at uhub0 port 2
uhub1: NEC hub, class 9/0, rev 1.00/1.00, addr 2
uhub1: 4 ports with 4 removable, bus powered
ukbd0 at uhub1 port 1 configuration 1 interface 0
ukbd0: Alps Electric M2452, rev 1.00/1.01, addr 3, iclass 3/1
wskbd0 at ukbd0
ums0 at uhub1 port 2 configuration 1 interface 0
ums0: Logitech M4848, rev 1.00/5.00, addr 4, iclass 3/1
ums0: 1 buttons
wsmouse0 at ums0
wscons: wskbd0 glued to wsdisplay0
boot device: <unknown>
root on wd0a dumps on wd0b
root file system type: ffs

... and X11 works, but cannot boot from internal hard disk yet.
Open Firmware 3.0 seems very different from older 1.x or 2.x.

So, my bootptab is:
imac:ht=ethernet:ha=000502dd00f6:hd=/tftpboot:bf=netbsd
:-)