Google Places Search on the iPhone and Android now offers an option to show only business that are open. The feature is available in Places search and filters out not just restaurants that are closed but restaurants for which Google is not confident of their hours. I performed the following search yesterday afternoon for Restaurant Spokane:
It is not totally obvious from the screen shot but the ranking was significantly altered when the top two Places listing completely disappeared. Not because they were actually closed but because the listings were not claimed and Google had been unable to find their hours elsewhere on the net.
Bing recently noted while presenting at the GetListed Portland seminar that 50% of all restaurant queries are now originating on mobile phones. If that fact and this feature is not enough to motivate business owners to claim their listing and populate it with accurate information, I am not sure what is.