Hi,

I had a panic this evening while shutting down my laptop. Here is the
end of the msgbuf:

wsdisplay0: screen 4 added (80x25, vt100 emulation)
acpiacad0: AC adapter online
[...]
acpi0: power button pressed, shutting down!
syncing disks... done
unmounting file systems..
uvm_fault(0xca8abe00,0, 1) -> 0xe

dumping to dev 0,1 offset 264823.dump 383 382 ....

I've been able to get a core, but the kernel was not build with
debugging information, so the trace is not really helpful:

#0  0xc03a90df in cpu_reboot ()
[...]
#5  0xc03a524e in kdb_trap ()
#6  0xc03b39f5 in trap ()
#7  0xc0102cdf in calltrap ()
#8  0xc035ba89 in fifo_poll ()
#9  0xc035abeb in VOP_POLL ()
#10 0xc0328a9a in selscan ()
#11 0xc0328e95 in selcommon ()
#12 0xc0329149 in sys_select ()
#13 0xc03b3406 in syscall_plain ()
#14 0xc01004b7 in syscall1 ()

It looks similar to http://mail-index.netbsd.org/port-i386/2007/04/17/0007.html 
I'll update tonight to the latest -current and see if it happens
again ...
 
 - Arnaud