Just caught this development this morning (3/18).
**Update** Here is a little background on this screen shot. I was doing some research with the Google Adwords keyword tool when I noticed the number of searches next to the previous month's bars indicating the search volume. I had not seen that before, nor have I seen it since. I have heard of Google testing new features on their SERP, but in my experience new features are usually stick around in the AdWords interface and are announced in a timely fashion.
Click for larger image.
Thanks to SearchEngineLand for posting the story! Thanks for the comments, keep them coming.
About me. I am a seasoned search engine marketing professional open to consulting work. Contact me at adamap (at) gmail.com.