When doing this:

var a = new Array(a, b);

a.map(function() { });

in IE8 I get:

Object doesn't support this property or method

Is this method not supported in IE8, or do I have some other problem? I've had a Google, but get lots of Google Maps javascript issues/questions...

Edit: OK so IE8 and below DO NOT support the .map() function. Copy-paste the code from MDN here which will add the .map() function to the Array prototype exactly per the specs if not natively supported (and it seems to work perfectly).