These nifty new controls allow you to navigate Google results using computer keys. You activate the function by pressing any key, which displays a small graphic of three colorful balls next to the first result. Move the balls around the page with the U (up), J (down), H (left) or K (right) keys and press enter to view the result.
There are several shortcuts, including C (view cached page), S (view similar page) and others. Very useful if you don't like using a mouse, or are working on a laptop.
Well, it turns out that it was removed from the Google labs in March 2005. The project's newsgroup is still up, though. Since it's taken me 9 months to notice that it's gone, I guess I can't complain that I'll miss it too much.