Google added a new feature for users who search for a postcode or zip code online to the maps one box on the search results. Now, if you search for a zip code or postal code, Google will display a map with an outline around the area of that zip code or postal code.
This feature does not currently work on Google Maps itself but does work when you search Google web search for a zip code such as , which is in Manhattan, New York. It also works for postal codes in London and other locations.
Here are some screenshots: