You can now enter an IP address as a search query and get the DNS information available, including the host name -- if available.
Is there any special way to enter the IP addresses? I found some IP addresses as visitors to one of my websites and put the IP address into Shablast. It threw an error when I entered it with hyphens between the numbers, as the statistics were showing, so I used spaces instead. This brought up possible sites, but none of the top ones was the actual IP address that I had entered. Mainly, it showed some site called honeypot which did not have the same IP address as the one entered.