In what top scientists are calling "pretty gay", Solaris can't handle disks that used to have non-solaris stuff on them without being wiped first.
I thought only the windows installer borked if the partition table
looked weird, but no! The installer could not see the disk, and I
was dropped into a dtterm where I had to do
of=/dev/dsk/c0t0d0 bs=1048576 and reboot.
So... wipe the disk before trying to install Solaris.