To follow up to my own messge, I've narrowed down where the problem is.

After compiling about a zillion kernels over the last two days, it seems
that the AirPort driver conflicts with some combination of USB, Cardbus,
and PCMCIA ethernet drivers.

I haven't figured out which of these is the problem, but I definitely need
to disable at least one driver from USB, Cardbus, and PCMCIA.

Since that leaves 10 drivers, it's going to take a really long time to go
through all combinations and figure out which one (if not all) that are
conflicting.  I'd rather not waste my time working on this when I could be
working on updating the 1.5.3 INSTALL notes.

Can someone shed some light on why/how removable ethernet devices conflict
with AirPort?  I ended up removing the following to get a working
almost-GENERIC kernel:

#ep*     at pcmcia? function ?           # 3Com 3c589 and 3c562 Ethernet
#mbe*    at pcmcia? function ?           # MB8696x based Ethernet
#ne*     at pcmcia? function ?           # NE2000-compatible Ethernet
#awi*    at pcmcia? function ?           # BayStack 650/660 (802.11FH/DS)
#wi*     at pcmcia? function ?           # Lucent WaveLan IEEE (802.11)
#ex*     at cardbus? dev ? function ?    # 3Com 3C575TX
#tlp*    at cardbus? dev ? function ?    # DECchip 21143
#rtk*    at cardbus? dev ? function ?    # Realtek 8129/8139

#aue*    at uhub? port ?         # ADMtek AN986 Pegasus based adapters
#cue*    at uhub? port ?         # CATC USB-EL1201A based adapters
#kue*    at uhub? port ?         # Kawasaki LSI KL5KUSB101B based adapters

And no, it wasn't just "wi at pcmcia?" and "awi at pcmcia?".  That would've
been too easy.

BTW, to make the whole thing more frustrating, adding the following makes
the problem go away (especially since this is the first thing I add to a
kernel config):
options    OFB_ENABLE_CACHE

Any help would be appreciated so I don't have to waste more time on this.

  -- MW