Just tried installing 1.3b1 on my Soekris NET4801 which has been running 
m0n0wall v1.22 for months... alas it did not
come back up after the firmware update.

Watching the reboot sequence via the NET4801's serial console showed the 
reason why:

The "ad0" driver was repeatedly failing attempting to do DMA to the 
CF-card... which is an old issue which cropped up
in older m0n0wall versions and was patched a long time ago.

Apparently the patch to disable the "ad0" driver DMA which Manuel put into 
the later1.2x versions to avoid problems
on the NET4801 with CF-cards which report themselves as "DMA-capable", 
didn't get applied to 1.3b1.

History: http://m0n0.ch/wall/list-dev/showmsg.php?id=3/16

The 128MB SANdisk CF card I was using with M0n0wall v1.22 did NOT work with 
1.3b1, (boot failed trying to do
DMA to the card), so I went rummaging through my junk box to try and find a 
non-DMA CF card... finally switched
to using a 64MB Kingston CF card, which booted 1.3b1 successfully in PIO 
mode.

Most CF card seller's don't distinguish between "non-DMA" vs "DMA" versions, 
so finding a "non-DMA" CF card
can be problematic, my 64MB Kingston CF card worked, but I suspect they 
house-brand from many manufacturers,
another lot might be different.

I believe Transcend explicitly sells industrial-grade CF cards with specific 
part numbers for non-DMA vs DMA versions:

Transcend: 
http://www.transcendusa.com/Products/ModDetail.asp?ModNo=15&LangNo=0

Anyway, for anyone using a NET4801, make sure you have a "non-DMA/PIO-only" 
CF-card on hand
before trying 1.3b1.

Personally, I'd vote for disabling DMA in future versions to avoid this 
issue.

-kevin