Diacritics automatically transformed to ASCII?

I'm experiencing a crazy problem where diacritics (ü,é,á) are automatically being transformed to ASCII (u,e,a) in my ActiveRecord objects. I know see that the data is properly encoded (UTF-8) in the DB, but when put into the ActiveRecord object, the diacritics are gone.

I can't figure out where this transformation is happening. It seems it could be happening anywhere in the rails stack. Has anyone ever seen this?

We're running an Oracle DB, Ubuntu, Ruby 1.8.6 patchlevel 111, and Rails 2.3.2.

What other information might be useful to find the problem?