Are you looking for something like the
mx.utils.ObjectUtils.getClassInfo() function? It looks as though
you could do something like:
var o: Object = ObjectUtils.getClassInfo(myObject);
You could then look at the class name using the "name"
property. If you want the actual class of the object then I cannot
help. I have tried to find this same information to no avail. There
is, of course, a Class class, and it is possible to create
instances of that class, and even to use instances of that class to
instantiate instances of other classes. But I haven't figured out
how to use the equivalent of Java's reflection capabilities in AS
(if it is even possible).