[development] custom form elements

Hi, I need to let users submit locations in a form (using googlemaps) and I was thinking if it is possible to define custom form fields for formapi? Like $map = array('#type' => 'map', '#default_value' => 'xxx yyy', '#title' => 'your location') and have this show up as a map in the form. Is it possible to do this? How should this be done? Thanks, Domas