variable_get

Depending on what phase the bootstrap is at, this function with either return the section from $conf or the merged database/$conf array (ie, the resulting array from variable_init()).

This is an issue for us as if the user admin area generates a server/cluster/bin which is required before bootstrap has given us the variables table then we're pooped.

I'm making this issue because I think it will need to be documented somewhere that if you want to use memcache for something which is to be cached DRUPAL_BOOTSTRAP_SESSION then you NEED to have your settings in settings.php.