An alternative to Phork/it's current demo.js nav positioning method. This will slide the nav on scroll rather than fix its position.

alt-nav-demo.js

var $nav = $('div.columns .column.right').each(function() {
	var $this = $(this)
		$window = $(window),
		$document = $(document)
	;
	
	if ($this.height() + $this.offset().top < $window.height() - $('#footer-shift').height()) {
		$this
			.data('top', $this.position().top)
			.css('position', 'absolute')
		;
		
		$document.bind('scroll', function(immediate) {
			clearTimeout(timeout);
			var timeout = setTimeout(function() {
				$this.stop().animate({
					top: Math.max($document.scrollTop(), $this.data('top')) 
				}, 1000);
			}, immediate ? 0 : 500);
		}).trigger('scroll');
	}
});