You cannot use a wildcard like that. You need to use the following code.
<ul id="userNavigation">
<li><?php echo l(t("Profile edit"), 'user/' . $GLOBALS['user']->uid . '/edit'); ?></li>
<li><?php echo l(t("My posts"), 'user/' . $GLOBALS['user']->uid . '/track'); ?></li>
<li class="exit"><?php echo l(t("Exit"), "user/logout"); ?></li>
</ul>
The global $user is the user object for the currently logged-in user. Be careful: It is not a fully-loaded user object. If you need that, you should use the value returned from user_uid_optional_load().