If the install routine for media-gfx/sane-backends would add a udev .rules file consisting of: BUS=="scsi", sysfs{type}=="6", GROUP="scanner" (type 6 seems to be for scanners) it would stop me from having to do this every time I set up a system. And all SCSI scanner users would get their sg* devices in the proper scanner group. And for that they would love you forver. Or is it a no-no for non-core packages to go adding udev rules?
Sounds good. Could take some time until I actually do this, though. Currently quite busy with my son (two weeks old).
I tweaked the sane-desc tool of .18 to emit this entry, please test .18-r1 which should hit your portage mirror soon. Thanks for the hint. Please re-open if there are problems with it.