This is the software publisher's description.

This much-requested chunk of Javascript to zoom images inline, originally written for this blog but later rolled out to the Panic website and used for screenshots, is now polished up, bug-fixed, available for you to use on your website!

Designed to view full-size photos and images inline without requiring a separate web page load, FancyZoom's raison d’être (French for " raisin-determination") is providing a smooth, clean, truly Mac-like effect, almost like it's a function of Safari itself. Since I originally wrote this script, there are now a lot of image zoomers to choose from (including a similar effect now on Apple's own site!), such as the popular (and inspiring) Lightbox.

FancyZoom does not require additional Javascript files to operate, which means that if the web user has Javascript turned off, they can still preview your photos. The operation is smooth and images pre-loaded, so no wait for the larger image to appear on screen.