In early September, Google announced the new Sitelinks Search box. It basically enables you to control how the search box within Google's search results sitelinks works with your site, that is, if you have a search box come up.
But if you do not want a sitelink search box to come up for your branded name, you can now disable it. A meta tag is available to disable it, the meta tag is:
<meta name="google" content="nositelinkssearchbox">
Using this will tell Google not to show a sitelinks search box when your site appears in the search results. The sitelinks search box will be disabled as part of the normal Googlebot crawling and processing of the page, which can take a few weeks depending on the site and other factors.
Menashe Avramov spotted this...
Forum discussion at Google+.