I have been wondering why the texts under Google advertisements have all changed from "Ads by Google" into "Ad Choices". And why Google has its Leaderboard advertisement style changed also. But I think Google Adsense has found that "Ad Choices" seems to be better that the previous one. Why I think so? It's because that the word "Ads by Google" probably has caught the sight of every blog or website readers. And this also makes the readers know that the ads are just ads, no matter how you blend them into looking like contents. And what I think is that when people know directly that ads are ads, they probably won't click on them.
Anyway, I do believe people will directly click whenever they are in need or curious about the contents of the advertisements shown by Google. So, I don't find a need to really blend them unless you need you blend in order to make it look neat. That's why I think.
About the leaderboard change, I really like it that way. It seems to fit more advertisements into the new leaderboard rather than the old one. Don't you think so? It also looks nicer with smaller text and longer text. Big gaps or spaces inside an advertisement will always make your blog seems weird. I dislike the Large Rectangle when it shows only one ad text at the center of the whole rectangle.
No matter how they change, I do believe that Google will keep on improving to suit the need of advertiser and publisher. There's a link here where you can read more why Google changes the name of ads into "Ad Choices".