On Fedora 8 x86_64 I got the proprietary Epson scanner software
"iscan":

iscan-plugin-gt-9400-1.0.0-1.c2.i386
iscan-2.10.0-1.c2.i386

to work by restricting the sane packages to i386 and the following:

sane-backends-libs-1.0.19-10.fc9.i386
sane-backends-1.0.19-10.fc9.i386

However on Fedora 9 x86_64 this trick didn't work, the iscan gui came
up but clicking on "Preview" result in a "warming up" status message,
but also, "Could not send command to scanner. Check the scanner's
status" and there was no preview scan.

I found that by commenting out the "epson", "epson2" and "hpaio" lines
in /etc/sane.d/dll.conf that the iscan/scanner starts working.

Hope this helps someone else out there.

Bob L.