Get the current map style, even in automatic mode, in Bing Maps AJAX 7.0

gistfile1.js

var map = new Microsoft.Maps.Map(
	document.getElementById("map"),
	{
		credentials: "YOUR-BING-KEY",
		mapTypeId: Microsoft.Maps.MapTypeId.auto
	}
);

Microsoft.Maps.Events.addHandler(map, "imagerychanged",
	function(){
		var style = this.target.getImageryId();
		//
		// "style" contains the type of imagery being displayed
		//
	}
);