When using the tab key to move the focus, there is no visual indication that an area element received focus.
Also, when using the same map for multiple images, the area should get focused once per each image.
Firefox, Opera, and WebKit based browsers do not properly support multiple images using the same map, but Internet Explorer does.
See the note at the bottom of the section http://www.whatwg.org/specs/web-apps/current-work/multipage/the-map-element.html#processing-model :
"Note: Because a map element (and its area elements) can be associated with multiple img and object elements, it is possible for an area element to correspond to multiple focusable areas of the document."
*** This bug has been marked as a duplicate of bug 36044 ***