First of all - I like to say that I love the media enhancement on 3.5. Well done.
I tested the functionality on some test users after embedding some images as thumbnail via one of my sites, http://paddler.co.nz.
Unfortunately, when the user clicks on an image, it takes the user to a new page on full screen view - some users struggle to get back to where they were.
This would have been resolved by having a neat JQuery lightbox to display the image if the user clicks on it - instead of leaving the page. Is this possible to have one in the final version of 3.5? If not does anyone aware of a plugin that would do that - but nothing more - as I love the way WordPress media manager does everything else.