37 Signals Style Lightbox | How to do this?

Does anyone know how 37 Signals built the pop ups for image previews that are now in basecamp? I really like how quickly they load and the fact that the whole page doesn't get "light-boxed" and there is a minimal border It's very snappy. You can see this effect on the marketing page for campfire:

http://campfirenow.com/?source=37signals+home

Just click one of the images below plans and pricing.

Is this custom javascript? Are they using a certain javascript 开发者_Python百科library? Anyone know?

Have a look at:

http://campfirenow.com/sprockets.js

and search for setupZoom()

The method being used for the clicks is zoomClick()

It looks like they're using FancyZoom to do the work and this is being combined with the Prototype Javascript Framework.

Cool Thanks!

I also found this: http://www.highslide.com/

It's a really similar effect that doesn't require Prototype.