Workaround for symlinked plugins when using wp_enqueue_script and __FILE__. See http://core.trac.wordpress.org/ticket/16953 and http://wordpress.org/support/topic/plugins_url-output-erroring?replies=5 for references on this.

gistfile1.php

<?php

// Fix the __FILE__ problem with symlinks.
// Now just use ___FILE___ instead of __FILE__

$___FILE___ = __FILE__;

if ( isset( $plugin ) ) {
	$___FILE___ = $plugin;
}
else if ( isset( $mu_plugin ) ) {
	$___FILE___ = $mu_plugin;
}
else if ( isset( $network_plugin ) ) {
	$___FILE___ = $network_plugin;
}

define( '___FILE___', $___FILE___ );

// Here we use ___FILE___ instead of __FILE__
wp_enqueue_script(
	'my-script',
	plugins_url('my-file.js', ___FILE___),
	array(),
	'',
	false
);
	
?>