that's JQzoom !

Purpose of this hack:
While the smaller thumbnail image is displayed in your post, the corresponding larger image is displayed inside a floating window only when the reader hovers his/her mouse cursor over the thumbnail-image. The image displaying-style inside the floating-window is exactly like that of a view through a magnifying lens or that of a microscopic view.
To get a clear idea of the hack,
check out the Live Demo... (in a Blogger blog).
And another standalone DEMO
Now follow these instructions to add this hack to your Blogger/BlogSpot blog:





















