Just want to report back that so far firewing1's module is working very well. No bugs to report.
With all of the help here and especially with firewing1's module I've mostly been able to get a Bilingual Ubercart installation to work.
There are still a few outstanding issues though:
1- On the checkout page, the cart contents pane always lists the products in English, even when viewing the checkout in another language.
2- The Catalog listing and the Language Switcher don't seem to work together well. My guess is that for some reason, the catalog block isn't able to lookup the localized versions of the taxonomy terms.