Since Phonegap version 0.9.5 the orientationchange event is triggered on the document object instead of the window object. This might be a problem as most libraries (amongst jQueryMobile) expect the event to occur on the window object.

However, there is an easy solution (this one requires jQuery but can be easily adapted):

$(document).bind("orientationchange", function(event){
  $(window).trigger(event);
});