Oh another thing I've noticed is that once boot gets running I can no
   longer break to the monitor - I have to power cycle the box.

this is cuz interupts are disabled.  fixing this is down the bottom
of my todo list and may not ever get addressed (by me).
   
   Hmmm maybe that 974816 _is_ magic, I just tried again and hung at the
   same point...

i've seen these hangs when i booted a kernel compiled with -g over
the net.  when i strip -d'ed the kernel, it booted fine.