A project to get the HP scanjet 4600/4670 see-through scanner works under linux. There is no release yet, but the code is available through svn. Actually, the backend is unable to scan anything, but the HP4670 is well recognized by Sane/XSane
This is the repository for experimental driver code for Canon 1220U scanner. See CVS for actual code. canon is for Linux utility. ucanoscan is for FreeBSD. As of long ago the desired functionality has been available as part of SANE project.