Hi,
I have tested flashrom r1129 on an Gigabyte K8M800-8237 mainboard with SST39SF040 flash. Probe, read, erase and write all work.
This board seems to be identical to GA-K8VM800M rev 2.x: If I use bios_extract to unpack the files from an image obtained with flashrom -r, do the same with version FD downloaded from http://download.gigabyte.ru/bios/motherboard_bios_ga-k8vm800m(rev2.x)_fd.exe (7zip format) and then compare them with "cmp", all files are identical. Also, dmidecode for K8M800-8237 lists "FD" as the BIOS version.
I was not able to actually open the box and look at what was printed on the PCB (can do that later if needed). Maybe product name and DMI-info always differ for Gigabyte boards. At least that seems to be the case for this unsuccessful test report with flashrom r1000 for the same(?) board: http://www.flashrom.org/pipermail/flashrom/2010-May/003169.html
Latest BIOS for (GA-K8VM800M rev 2.x) can be downloaded here: http://www.gigabyte.com/products/product-page.aspx?pid=1919
Thanks! -mattias