I'm very pleased with the ultimate shortcodes plugin. I have 1 issue though:
Using the gn_gmap shortcode within a gn_tab results in a centering problem (in some browsers and not always probably due to caching). When this occurs the pointer is exactly in the top left corner and only visible after moving the map.
Google Map example within a tab can be found at: http://www.gilbertkoskamp.com/wp/woonhuis-oegstgeest/ , klik the tab named "kaart".
Now there quite a few discussions going on about googlemaps not showing up inside jquery tabs (do a search) and the problem seems related with the google map not having any reference point. When the map is loaded the tab content area is still hidden and thus the map loads in the top left.
Most solutions suggest a "google.maps.event.trigger(map, "resize");" when the tab with the map is clicked.