Search Cube is the latest in a string of search engines that forgoes displaying search results in an easy-to-parse, ordered list, in favor of a whiz-bang 3D interface. It grabs its results from Google and site preview thumbnails from Thumbshots, then combines them in a 3D cube that you can rotate freely either with your mouse or keyboard.
What's clearly missing here are which results are worth clicking on, something you get with Google's search result relevance algorithm. On the flip side (literally), you get to see a lot more results at once, and with a little visual flair.
Where I think this engine could really be useful is in providing a better preview of the source page, along with letting you know how relevant a result it is. As it stands, clicking on any of the results takes you off the engine and into a new tab or window. It would be much simpler to open up a full preview of the page where you could view the content akin to tools like SearchMe.
Here's a quick demo of what it looks like (a higher-quality stream should be live soon):