This image, computer-drawn by Nasa, gives you a feeling for the vast cloud of space junk flying around the earth at both low altitudes and even in the 23,000-mile-high geosynchronous ring where the big communications satellites hang out (a low-earth-orbit version, also by Nasa, is seen here on Space.com). Of course, there is lots of space between the dots in real life. But as more gear is lofted into space, the problem of space junk will only grow. Maybe we need orbital junk men to clean things up. As one commenter to the Space.com noted, where is Sanford and Son when you need them?
Here is an animated video showing how the iridium satellite and Cosmos 2251 collided with a reported closing speed of more than 15,000 mph.