Google experiments with a slightly different search interface for tablets. There's a new settings button below the search box that lets you disable SafeSearch and use the advanced search filters. The most popular specialized search engines are no longer hidden behind a small arrow: the new interface mimics the desktop UI and displays a list of search engines, followed by a "more" link. It's quite obvious that the navigation bar starts to become unnecessary, now that the settings button and most navigation links are displayed below the search box.
Three months ago, Google launched an interface optimized for iPad and Android tablets.