Today I noticed that on English version of Google Ads (AdSense) showing AdChoices instead of Ads by Google.
I found explanation for that on AdSense blog: http://adsense.blogspot.com/2011/03/new-in-ads-notice-label-and-icon.html
You've probably noticed that AdWords ads appearing on your site have a special "i" icon that expands to an "Ads by Google" label in the bottom corner of the ad. Users who click this label are taken to a page where they learn more about online advertising and the ads they've seen. Giving users clear notice about the ads they see is a high priority for Google and for many in the online advertising industry at large.
We'll soon start to change our in-ads notice icon to a new icon that expands to an "AdChoices" label. These notifications were developed by the online advertising industry’s Self-Regulatory Program for Online Behavioral Advertising to more proactively give users notice and choice about the ads they see. With the change from our "i" icon and "Ads by Google" label to these new notifications, we hope to show our support for this cross-industry initiative, and to increase our users' understanding about ad choices through adoption of an icon they'll see on ads across the web.
This statement was made on Monday, March 21, 2011, and as per Google they will roll out this change in a few weeks, i.e. in the beginning on April, and on English versions only.
Read more about Google AdChoices here.