Ha! I knew it! After a few emails, I finally got a confession out of Mr. Masato. He says,
00 12 * * * /usr/bin/env LD_LIBRARY_PATH=/opt/oracle/lib /path/to/script.rb
or set LD_RUN_PATH (or ld -R option) at the compile time [using mkmf for example].
LD_LIBRARY_PATH and cousins (LD_RUN_PATH) are strange beasts. There's a document out there that not only explains LD_LIBRARY_PATH (and why you should hardly ever use it in the way many people suggest) but also helped me to think in new ways and expand my horizons. I'd rate it as one of the fundamental inputs that helped me to become a better programmer, designer, and thinker. It's also the first document you'll find if you plug LD_LIBRARY_PATH into Google.
Not sure if anything in this essay relates to your issues with the variable, but I figured it never hurts to mention.
