I have written my second Adsense article, it's titled "Making your Adsense rotate colour palettes". The aim of the article is to improve the CTR of your ad units. It can be located here - Adsense article. If you didn't get to read my first article, it was titled "Maximizing Adsense revenue with 6 easy tips" and there's a link to it in my signature.
i wansn't too interested in doing this, but is a good thing to know, anyway, now i don't find it usefull
it helps some times and attract visitors to ads. I use a rotator with one of my adblock. but not for every ad
It certainly attracts my eyes, rotating between adsense, YPN etc could also be good (if it's not against ToS).