I can report that I am able to read, write, and erase with a PCI-X Sata SIL3124 card. I see on the wiki that it shows a question mark. Note that I had to place it temporarily in a 5v PCI slot to get it to write. Seems the particular flash chip on my card is a 5v part.
Silicon Image SiI 3124 PCI-X SATA Ctrl 1095:3124 OK
Thanks to all for the incredible flashrom tool, my SATA controller wouldn't be working without it!
DISCLAIMER I know it's a wiki. However, this page says not to edit it directly, as (some) of the content is autogenerated from "flashrom -z output." I'm not a developer, and don't know how to patch any possible existing code to cause an autogenerated update of this info. This is just a report, and I hope this helps. Thanks.
-Mick