Yahoo's optimization wizards?

I climbed Google and wanted to find out that the new thread, except for shortcuts experiment, did not find anything, but by clicking on the News link, I saw the news about the new project. Yahoo Shine .

Having opened and scrolling to the bottom of the page, I almost closed the window, but noticed that the pictures on the site were loaded after the page was fully loaded. It turned out that Yahoo upload images only when they are visible on the screen using JavaScript. If the page is three sheets long, when you open the page, the pictures visible on the first sheet are loaded, and when you scroll down to the second sheet, the pictures from the second sheet are loaded, and so on.

I did not begin to disassemble the code, since there is no time, but I am sure that the code will soon be disassembled, improved, made a cloud of lessons and praised, and Yahoo will add it to their presentations :)
')
ps I am also sure that the idea is not new and was implemented earlier.