I just saw this on a web site – a technique for verifying I’m a human:
The stupid thing that made me post is that the only thing that resembles a clock is the round green circle thing. The rest are obvious. If you’re going to make someone identify the proper shape – make the icon actually look like the object! That’s a terrible icon for a clock (and odd grammar as well).
Zoomed:
Seriously?
Furthermore, why do I need to drag the clock into the circle? Why wouldn’t just a click on the right icon be enough?

My guess is because it’d be easier for a bot to recognize the images and simulate a click than to drag them. Of course, if someone goes through the effort to do the matching, doing the drag is probably pretty easy, too.
Wonder if this is iPhone compatible, though – I know there are drag/drop issues with missing DOM events…