This plugin allows you to customise the title attribute and menu label of each page link in wp_list_pages() or wp_page_menu().
I have it on a site I’m building on WP v3.21 and also on a cloned version of exactly the same site with v3.3 b2. The plugin works fine on the site using v3.21, however any menu label setting in the v3.3 b2 installation has no effect.
Don’t think that would have anything to do with the pagename query_var, actually. I’m more concerned about custom rewrite rules by plugins potentially being broken. Title and menu labels wouldn’t be relevant to that.
The plugin is using a regex to modify the links produced by wp_list_pages(). Part of the regex pattern looks for title="([^\"]+)" however in WP 3.3b2 the title attribute has been left out of the links (in the Walker_Page class), and therefore the plugin’s regex is not able to match.
Is the omission of the title attribute intentional in 3.3b2?