It took awhile, but WP 2.6 now allows the wp-config.php file to be moved above the area that the public can access.
When WP needs to access the config file it knows to look for wp-load.php, which in turn will access the relocated config file.
Unfortunately, some plugins look specifically for the config file and know nothing about wp-load.php. In one case where this occurred was resolved by changing all instances of wp-config.php to wp-load.php and the plugin worked fine. The plugin developer was contacted and has fixed the problem and due to release an update to address the issue.
WP does not include in their plugin compatibility test a test for a relocated config file. I know this because the plugin that brought the issue to light is listed as being compatible with WP 2.6--and it is not.
I was wondering if others who have relocated the config file have also found this a problem with plugins.
It would be great if WP's compatibility test included the relocation of the config file.