Tom Johns posted a picture of this in action in a Google+ Community thread saying he is running a beta of Chrome and the search box is gone. Now, he has to search by using the Omnibox within Chrome. So he has to replace the URL string of the search results with a query. Not a big deal but I'd assume this is confusing for some searchers?
Here is a picture:
You can reproduce this yourself without running the Chrome beta by using this special URL parameter when searching. Here is a sample search for google in Google search.
Forum discussion at Google+ Community.