I installed netbsd on a Macintosh Quadra-610 yesterday, and today I was
able to cross-compile the kernel, which booted fine, to my delight.
Here's the dmesg output for anyone who is interested:

Copyright (c) 1996, 1997, 1998, 1999, 2000, 2001, 2002, 2003
    The NetBSD Foundation, Inc.  All rights reserved.
Copyright (c) 1982, 1986, 1989, 1991, 1993
    The Regents of the University of California.  All rights reserved.

NetBSD 1.6ZD (GENERIC) #0: Fri Oct 24 01:45:03 PDT 2003
	gross@gospel.xinetd.com:/usr/obj/sys/arch/mac68k/compile/GENERIC
Apple Macintosh Quadra 610  (68040)
cpu: delay factor 800
total memory = 20480 KB
avail memory = 14884 KB
using 281 buffers containing 1124 KB of memory
mrg: 'Quadra/Centris ROMs' ROM glue, tracing off, debug off, silent traps
mainbus0 (root)
obio0 at mainbus0
esp0 at obio0 (quick): address 0x898000: NCR53C96, 16MHz, SCSI ID 7
scsibus0 at esp0: 8 targets, 8 luns per target
adb0 at obio0
asc0 at obio0: Apple Sound Chip
intvid0 at obio0 @ f9001000: DAFB video subsystem, monitor sense 1
intvid0: 640 x 480, monochrome
macfb0 at intvid0
wsdisplay0 at macfb0 (kbdmux ignored): console (std, vt100 emulation)
sn0 at obio0: integrated Ethernet adapter
sn0: Ethernet address 08:00:07:9c:81:ac
iwm0 at obio0: Apple GCR floppy disk controller
iwm: Chip revision not supported (-77)
zsc0 at obio0 chip type 0
zsc0 channel 0: d_speed   9600 DCD clk 0 CTS clk 0
zstty0 at zsc0 channel 0
zsc0 channel 1: d_speed   9600 DCD clk 0 CTS clk 0
zstty1 at zsc0 channel 1
nubus0 at mainbus0
fpu0 at mainbus0 (mc68040)
adb0 (direct, II series): 2 targets
aed0 at adb0 addr 0: ADB Event device
akbd0 at adb0 addr 2: extended keyboard
wskbd0 at akbd0 (mux ignored): console keyboard, using wsdisplay0
ams0 at adb0 addr 3: 1-button, 100 dpi mouse
wsmouse0 at ams0 (mux ignored)
scsibus0: waiting 2 seconds for devices to settle...
sd0 at scsibus0 target 0 lun 0: <CONNER, CP30175E-170Mb, 5.23> disk fixed
sd0: fabricating a geometry
sd0: 162 MB, 162 cyl, 64 head, 32 sec, 512 bytes/sect x 332488 sectors
sd0: async, 8-bit transfers
sd1 at scsibus0 target 1 lun 0: <IBM, DALS-3540     !s, S60E> disk fixed
sd1: fabricating a geometry
sd1: 516 MB, 516 cyl, 64 head, 32 sec, 512 bytes/sect x 1056768 sectors
sd1: sync (248.00ns offset 15), 8-bit (4.032MB/s) transfers, tagged queueing
boot device: sd1
root on sd1a dumps on sd1b
sd1: fabricating a geometry
sd1: fabricating a geometry
sd1: fabricating a geometry
sd1: fabricating a geometry
sd1: fabricating a geometry
sd1: fabricating a geometry
root file system type: ffs


Regards,

Glendon Gross