Boo, deleted short tags. Why do people hate short tags again? I can't remember because <? is not valid XML so there shouldn't be any problems with mixing php and xml... hmm... I wonder ....
<?= always exists as of PHP 5.4, despite the short tags setting.
With echo tag you can have a very simple and powerful templating system written in the language itself. (I usually just use two methods, Temaplte::show and Template::get, which both are less than 20 lines long.)