Today I discovered one problem with rich:gmap component.
If it is used inside a rich:tab, which is not a first tab in the tabPanel and switch type is "ajax" google map is not rendered and browsers gets frozen.
If switch type is "client" it starts to work, though map area is not rendered completely, it has some blank part at right side.
Unfortunately, gmap can't be rendered via ajax.
So you need to make the tab switched via server mode.
Hope it helps.