I have been working with WordPress solid for the past few weeks. I have only used it off and on until then. I like it a lot, but I am blown away at how little versatility is provided with the new menuing system.
There is no easy way to make a breadcrumb menu, there is no easy way to check if a given page is a child or parent in a custom menu, etc.
I think that there should be a simple way to get the data the wp_nav_menu uses to return an HTML menu and have it returned as an object or array so that custom functions can more easily be written to extend the functionality of the new WordPress 3 menus.