OK, so my first thoughts were "what are those things?" So were my second and third thoughts, actually. Is it the national day of some obscure country which has an association with colourful computer components? Is it a major festival I'm unaware of, celebrated through the consumption of metallic lollipops?
Ah, but what's this? "What happens when great art mixes with your homepage? iGoogle Artist Themes"
So that's what it is: art. I'm supposed to have my thoughts provoked by it. I'm not entirely sure how this is intended to benefit me, but OK, job done.
Now, how do I switch it off?