Allow properties to be recursively named.

I've implemented this myself. ProjectConfigurator::replaceProperties should be edited as follows:

public static function replaceProperties(Project $project, $value, $keys) {
if ($value === null) {
            return null;
        }
        
        // These are a "hack" to support static callback for preg_replace_callback()
        
        // make sure these get initialized every time        
        self::$propReplaceProperties = $keys;
        self::$propReplaceProject = $project;
        
        // Because we're not doing anything special (like multiple passes),
        // regex is the simplest / fastest.  PropertyTask, though, uses
        // the old parsePropertyString() method, since it has more stringent
        // requirements.

        // Following loop added 21/08/08 by Ela Boosh to allow replacement
        // of nested tokens.
	$sb = $value;
	while (strpos($sb, '${') !== false)
	{ 
                // old reg exp for single passes
        	//$sb = preg_replace_callback('/\$\{([^}]+)\}/', array('ProjectConfigurator', 'replacePropertyCallback'), $value);
                // new reg exp.
		$sb = preg_replace_callback('/\$\{([^\$}]+)\}/', array('ProjectConfigurator', 'replacePropertyCallback'), $sb);
	}

        return $sb; 
}

a better version that will not allow for an infinite loop when the value can't be replaced is below:

public static function replaceProperties(Project $project, $value, $keys) {
if ($value === null) {
            return null;
        }
        
        // These are a "hack" to support static callback for preg_replace_callback()
        
        // make sure these get initialized every time        
        self::$propReplaceProperties = $keys;
        self::$propReplaceProject = $project;
        
        // Because we're not doing anything special (like multiple passes),
        // regex is the simplest / fastest.  PropertyTask, though, uses
        // the old parsePropertyString() method, since it has more stringent
        // requirements.

        // Following loop added 21/08/08 by Ela Boosh to allow replacement
        // of nested tokens.
        $sb = $value;
        $iteration = 0;
	while (strpos($sb, '${') !== false)
	{ 
                // old reg exp for single passes
        	//$sb = preg_replace_callback('/\$\{([^}]+)\}/', array('ProjectConfigurator', 'replacePropertyCallback'), $value);
                // new reg exp.
		$sb = preg_replace_callback('/\$\{([^\$}]+)\}/', array('ProjectConfigurator', 'replacePropertyCallback'), $sb);

                // keep track of iterations so we can break out of otherwise infinite loops.
                $iteration++;
                if ($iteration == 5)
                       return $sb;
	}

        return $sb; 
}