Having followed every instruction on every 13 year old's blogiwikilivejournal within Google's reach, I have yet to come across any method of running multiple Rails applications from a single domain under Apache that actually works with the current version.
If I create a symlink to the application's public directory within my document root and add a RewriteBase directive to its .htaccess file, dispatch.cgi runs just fine, but I am still ultimately treated to a nebulous 500 error, as initializer.rb isn't smart enough to realize that it's running in a different directory, and goes searching in the document root via ".." for /config/environments/development.rb etc. I have a feeling that the commented example Alias directive in the .htaccess file might resolve this issue, but users on shared servers do not have access to their own httpd.conf files, so it's not really a viable option since the directive is not legal anywhere in an .htaccess file that I know of.
This may or may not be a bug, but if there is a simple configuration related resolution for the problem that does not require administrative access, I could not find it documented anywhere. Seeing as how this seems to be an incredibly common problem a lot of people are having, there should be some notes in environment.rb pertaining to the issue at the very least.
It's also annoying that the application seems to be pulling Rails from the gems installation despite the fact that I explicitly "froze" the gems into the vendor directory for debugging purposes.
/usr/local/lib/ruby/gems/1.8/gems/rails-0.14.3/lib/initializer.rb:150:in `read': No such file or directory - /Users/username/Sites/config/environments/development.rb (Errno::ENOENT)
from /usr/local/lib/ruby/gems/1.8/gems/rails-0.14.3/lib/initializer.rb:150:in `load_environment'
from /usr/local/lib/ruby/gems/1.8/gems/activesupport-1.2.3/lib/active_support/core_ext/kernel.rb:27:in `silence_warnings'
from /usr/local/lib/ruby/gems/1.8/gems/rails-0.14.3/lib/initializer.rb:147:in `load_environment'
from /usr/local/lib/ruby/gems/1.8/gems/rails-0.14.3/lib/initializer.rb:78:in `process'
from /usr/local/lib/ruby/gems/1.8/gems/rails-0.14.3/lib/initializer.rb:40:in `run'
from /Users/username/Sites/depotpub/../config/environment.rb:10
from /Users/username/Sites/depotpub/dispatch.cgi:3
[Fri Nov 18 14:30:50 2005] [error] [client 127.0.0.1] Premature end of script headers: /Users/username/Sites/depotpub/dispatch.cgi