Installer fails to install GRUB when using XFS (AMD64 Flight 6)

Short version:  The installer failed to isntall GRUB when using XFS.
There *may* be other factors contributing to the problem.

My setup-
Ubuntu-server Flight 6, AMD64
Tyan Transport GT20 barebones rig (nForce 4 chipset, etc), Athlon 64 X2,
and...
3ware 8006-2LP 2 port raid controller, 2x250 drives as a RAID 1 mirror

Simple steps that *should* recreate the problem:
Install standard system, proceed through installer normally, and select
"Erase entire disk..." without LVM.  It'll show the parameters for
partitioning and formatting.
Select "Go Back" and change the filesystem type of the EXT3 data
parition to XFS.  Everything set up correctly, set as 'boot.'

NOTES:  I also selected "noatime" as a parameter, and possibly also
significantly, there was already an existing XFS partition from a failed
(bad install media/optical drive) previous installation, so the
partition type selected defaulted to "keep existing data," and I
selected "Format"

The entire installation process apparently completed successfully, but
at the end, GRUB failed to install.

I attempted to set up GRUB myself after the fact using the installer CD
in 'rescue' mode, but I failed with this as well.  This could have been
operator error, but I did get some weird XFS errors.  Not sure.

And yes, all the data was on the drive correctly, apparently, as I
verified using the rescue CD.  Just no bootloader!

I'll gladly provide any more details that I can from memory, but I may
or may not be able to re-create the situation again due to a sudden lack
of physical proximity with the box that I installed this on... =]

-Overand