General usability guidelines states users expect a search feature to contain besides the search field, a button labeled "search". Looking at recent designs of search, the button is disappearing. These lack the search button.
All Apple search, i.e. apple.com, Spotlight and iOS. They have a clear button. On iOS, the keyboard provides a search button.
Google Chrome. The address bar functions as a search and is activated by pressing Enter.
How much of a usability sacrifice is it to remove the search button in say interfaces that are compacted in a modal window?