SmartyPress is another Smarty driven WordPress project.
It looks interesting, and I had the thought that it might be possible to paste an alternative template system into WordPress by piggy-backing on top of the current system.
The home.php, single.php, index.php files of the various themes could be loaders for another more secure templating system rather than PHP. It would certainly make editing templates and securing them against abuse easier, although for WordPress.com we have even fancier ideas to be announced later!
will it work better than wordpress mu ?
It only handles a single-blog like WordPress does so it’s nothing like WPMU. It’s more like a rewritten WordPress.
There is a WordPress plugin, Smarty for WordPress that can load your existing smarty templates without modification either into a page/post using shortcodes or calling the famaliar smarty class api. You can download this great plugin from wordpress.org at http://wordpress.org/extend/plugins/smarty-for-wordpress/