With jquery-ui-1.7.x.js version works fine, but with newer version 1.8.x it gives me error
Uncaught TypeError: Object function (a,b){return new e.fn.init(a,b,h)} has no method ‘widget’
From what I saw in jquery ui downloads before 1.8 version there is no option to download “Widget” but in 1.8 you have a selection to download core and widget seperately. There is I believe the problem.
The author has developped a more compatible version of JCoverFlip with jQuery UI 1.8 at https://github.com/NewSignature/jcoverflip.
It works for me!