Google images is currently leveraging the social environment and users willingness to provide content to better label images for more efficient image searches. The product is called Image Labeler. Yahoo has Flickr, which allows users to add images and tag them online, but Google has taken a slightly different approach. They have turned this tagging into a sort of game, where you can earn points. Two users are paired, and shown images from various sites that have images already indexed in the engine. Each user enters descriptions, where they try and match their partner. Google claims that they are using the data collected from the users to better rank their index so that when a search occurs on Google images, more relevant results will populate the results.

The way the game works according to Google is:

You'll be randomly paired with a partner who's online and using the feature. Over a 90-second period, you and your partner will be shown the same set of images and asked to provide as many labels as possible to describe each image you see. When your label matches your partner's label, you'll earn some points and move on to the next image until time runs out. After time expires, you can explore the images you've seen and the websites where those images were found. And we'll show you the points you've earned throughout the session.

This is just another reason to optimize your images on your web site for search engines. The higher an image comes up on Google images, the more likely you will receive additional web site traffic, especially if your image is representative of your web site theme.