Does get_defined_vars() show variables defined in variable_set()? I'm using Drupal 6, and I'm having problems retrieving a set of variables I set with variable_set() using variable_get(). I'm doing a dpr(get_defined_vars()) to see what's defined, and I don't see my variables; I see only the arrays $form and $form_state (this is inside hook_submit()). 

Does get_defined_vars() show all the variables defined via variable_get()/variable_set()? I would just like to see a list of all of them. I just need to see if they've been set correctly, and troubleshoot why I can't retrieve them.
get_defined_vars is a PHP function, not a Drupal function.  It basically shows you all variables that are in scope.

Drupal variables set by variable_set are not automatically within scope.

Variables are stored in global $conf; but I don't recall if non-variables are also stored here.

If you install the Devel Module there is a page for viewing and editing variables.

EDIT:

Curiosity got to me.  The variable editor in the Devel Module queries the {variable} table and not global $conf; to build the form of all available variables, so that suggests that is the proper way to do it.