I am a bit in shock to see Google testing yet another messaging on their simplistic fading home page. First it was just a plain and simple search box and logo, with no instructions. Then Google had to add instructions to tell people they need to press enter to conduct a search. Now, Google is taking it one step further by explaining that the page is left empty on purpose.
Here is a screen capture:
Yes, this is the type of stuff you see on standardize tests or big legal documents. Now, you see this on Google's home page.
We have some people complaining about this in the forums.
Forum discussion at Google Web Search Help.