Here is a little more info:
The last kernel that doesn't have the fdc0 problem reports the following:

fdc0 at mainbus0 ioaddr 0xf7200000 pri 11, softpri 4: chip 82072
fd0 at fdc0 drive 0: 1.44MB 80 cyl, 2 head, 18 sec

I notice that the chip number is different.

Brad

I previously wrote:

The problem I reported with -current is partly cured, X now starts, but I still
see the following:

fdc0 at mainbus0 ioaddr 0xf7200000  ...result:timeout
 CFGLOCK unexpected resp softpri4 chip 82077

I can't print dmesg, 

law:bsalai {101} dmesg
dmesg: magic number incorrect

This is with sources supped tuesday.

Brad