[Plugin: Read More Inline] here is the working js

Seems like everything works here, except clicking the link still takes you to the next page. Paste this JS over the stuff in ../read-more-inline/js/pobp_rmi.js

var $j = jQuery.noConflict();

$j('document').ready(function(){
	$j('.readmoreinline').hide();
	$j('.more-link').click(function(e){
		e.preventDefault();
		$j(this).empty().parent().next('.readmoreinline').show();
	});
});

http://wordpress.org/extend/plugins/read-more-inline/