Looks to me like we're a baby-step behind Windows in not having GUI wrappers or frontends for the steganography (?) binaries I mentioned above. Or have my searches just not turned up the obvious GNOME solution?

Also, can someone tell me exactly what image file format works in login screen face lists, in place of the "generic user" icon one? And is there a command-line workaround to get unique ones assigned per-user? The "Login Window" utility in Ubuntu 9.10 seems a bit insistent on using the same image and path to images for all user icons -- hardly a user-friendly way of making user A's identifying icon different from user B's.

BZT

Found it -- SteGUI http://sourceforge.net/projects/stegui/ (gzipped tarball -- no deb on SF as yet: I might be inclined to fill that gap with a checkinstall.)
According to LinuxPoison's blog, you need the following deps to install and run it:

• stegtools

• FLTK toolkit

• PStreams

• ALSA

• Libjpeg libraries

And on the other question/problem/gripe, there's this:

To add a user icon, Login Window doesn't even enter into the picture (npi). System>Preferences>About Me, for each user when logged-in as each, does! And JPEGs are fine. I'd like to thank WorMzy on this Ubuntu Forums thread for pointing it out.

BZT