Wissam Dandan sent me a note on Google + that Google is testing a minor change to the top bar.
Let me show you the difference between the test and what we see now.
Current Top Bar:
Google's Test Top Bar:
The main difference is that it reads "Search" directly under the logo and has the number of results directly under the search box in much larger type.
Ruben also spotted this test and posted a video in Google Blogoscoped Forums. In fact, there are three variations to the test and here they are:
Again, this is a small test but it does push the search results down a bit, which can obviously have an impact on your click through rate.
Forum discussion at Google Blogoscoped Forums.