I'm running a web site under a shared hosting environment (it's Dreamhost, if it makes a difference) and attempting to use SetEnv from within a .htaccess file.
Everything else in the .htaccess file is working fine and Apache is not generating errors.
Since SetEnv requires Override FileInfo (ref), I figure that's my problem. I have a Perl script dumping out %ENV to test my config changes, but nothing I've tried works.
How can I test that AllowOverride FileInfo is enabled?
While looking for references while writing the question, I found the answer. I figured I'd document my answer here in case anyone else has the same problem.
The SetEnv was working but the Perl script I was testing with runs under Suexec. According to this support document, Suexec strips off all environment variables that do not begin with HTTP_.