I have a simple test plugin - a folder called
tester containing a file called
tester.php that contains only this:
<?php /* Plugin Name: My tester */ ?>
I have a copy of WordPress running locally on my Mac. When the plugin is in the plugins directory it appears in the Admin list of plugins.
When I move the plugin directory elsewhere and symlink to it, it doesn't show up.
I've done similar with a theme, and WordPress happily uses that. From what I've read this should now work with plugins too. Am I missing something?