I just noticed the new "Ads" label today and did a quick search and found this from a few days ago...

<< Google has confirmed this rollout. The rollout is only on English language domains for now, but will roll out to additional languages in the future. A Google spokesperson said:

"Yes, I can confirm this rollout. We are always experimenting with the look and feel of our search result pages, including the delivery of relevant advertising. This is on English language domains now and rolling out to all languages and domains." >>

http://farm5.static.flickr.com/4021/5075317183_41101c070a.jpg

http://searchengineland.com/google-does-away-with-sponsored-links-label-now-ads-are-labeled-ads-54956

Sounds more casual, less corporate speak to me. Google might also be happy that it's shorter, thus perhaps less likely to stick out? Not sure... I suppose it's possible that if the click rates would have dropped, we might not have seen this one become rolled out :)