It’s called the Parallax effect. It’s a popular website trend going on now. I just used a theme for one of my client’s that uses this.
You can see the theme I used here: http://demo.drythemes.com/index.php?theme=dry-wp
Basically think of the New York Times building image as the main background. Instead of it scrolling with the content on the page (when you scroll down), it stays still and the content scrolls over it. With a good, detailed, hi-res image this effect can bring some life to an “old” site’s content.
Took too long to load, so I went somewhere else.
Often websites become so enamored of digital special effects that they forget the basics.