Can anyone reply here and elaborate on how exactly that "zoom" effect was made, because it's awesome, and DISQUS is the only place I've seen it. I have made a similar effect at http://myownstream.com and http://www.fotomozo.com/gallery?name=out4c2df5372f234.png but without the round lens.
To answer the question: it's done by having a 120px square div that:
* Has the full "zoomed" image as the background: http://mediacdn.disqus.com/1318540955/img/marketing/homepage...
* Has a thick white border, 120px border-radius and a box-shadow applied.
* Is absolutely positioned, with its top and left being controlled by javascript.
Also I think there is one more factor * The background position is probably being controlled by javascript as well
border-radius will work on Firefox and Webkit (but you'd best include the -moz and -webkit versions as well, for older versions that don't pay attention to the plain attribute).
It's a bit tougher with IE. IE7 and IE8 don't support border-radius, but support can be faked with something like http://css3pie.com/ or http://fetchak.com/ie-css3/