Heads up, the new fancybox, while having much better code, and in general better features and design, is not backwards compatible. Here is a (growing) list of things that you'll need to change:

  1. If you get "Syntax error unrecognized expression: [your URL]", you probably need to add type: 'ajax' in your fancybox constructor:
   $('a.fancybox').fancbox({
     type: 'ajax'
   })
  1. onComplete callback is now afterLoad
  2. $.fancybox.center is now $.fancybox.reposition
  3. $().fancybox({autoDimensions: true}) is now $().fancybox({autoSize:true})

I'm not upset, btw. I think backwards compatibility can stifle innovation for those who innovate best - people who make these great tools. You can keep using v1.3.4 for as long as you want, if you don't feel like upgrading, so I don't feel betrayed by having to fix a few things.