We have two desks in our living room about three feet apart. For a long time, we had our two gerbils in a fish tank with a heavy screen lid (the lid can support the weight of a fairly hefty cat (who happens to be the subject of this story but I'm getting ahead of myself)) on the second desk. Our cat, Guy Noir (he's black and my mom likes NPR), could use chairs to get onto the first desk but not the second, so he would get on the first desk and then leap the gap so he could sit on top of the gerbil tank and stare at them. He has been doing this for more than a year. Now, for whatever reason, my parents decided to move the gerbils to on top of the first desk instead of the second one, so Guy jumps onto the first desk, gets on top of the gerbil tank, and jumps to the second simply out of habit. When he lands, he gets this really perplexed look on his face, he cannot figure out where the tank went, despite him having been on top of it just a few seconds beforehand.
EDIT: Here are pictures of my three cats. The black one is Guy, and the two brown ones are Hailey and Ossie. http://www.facebook.com/album.php?aid=2075852&id=1397293712&l=e5a7118586