Excellent! This worked. I guess I need to learn more about this T
notation. For anyone following the thread here is the final solution:

public static void printOneDimension(Map<String,?> map){
       for(String k1:map.keySet())System.out.println(k1);
   }
public static  <T> void
printTwoDimensionsNew(Map<String,Map<String,T>> map){
       for(String k1:map.keySet()){
           for(String k2:map.get(k1).keySet()){
               System.out.println(k1+","+k2);
           }
       }
   }
public static void main(String[] args){
       Map<String,String> m1=new HashMap<String,String>();
       m1.put("a",null);
       m1.put("b",null);
       printOneDimension(m1);
       Map<String,Map<String,String>> m2=new
HashMap<String,Map<String,String>>();
       m2.put("x",m1);
       m2.put("y",m1);
       printOneDimension(m2);
       printTwoDimensionsNew(m2);

}

Here is the output:
b
a
y
x
y,b
y,a
x,b
x,a

Thanks,
Rob

I changed my code as follows:

      Map<String,String> m1=new HashMap<String,String>();
       m1.put("a",null);
       m1.put("b",null);
       printOneDimension(m1);
       Map<String,Map<String,?>> m2=new HashMap<String,Map<String,?

       //Map<String,Map<String,String>> m2=new
HashMap<String,Map<String,String>>();
       m2.put("x",m1); // Note I updated this to use m1 instead of
null
       m2.put("y",m1); // since you cannot print null.
       printOneDimension(m2);

       printTwoDimensions(m2)

And it compiled and printed results as expected:

b
a
y
x
y,b
y,a
x,b
x,a

That said, I don't want to declare the m2 with ? as a value and I
don't understand why I should have to.

If I declare m2 with the ? as shown, I have no way to get it back to a
Map<String,Map<String,String>>. Even if casting it back worked, it
would be a pain and I don't see why it is necessary.

My understanding of wildcard '?' is that it can represent any type but
it limits your ability to perform operations that require knowing the
type. This works fine with the function printOneDimension() as the map
parameter is declared as a Map<String,?> and we never accesses the ?
(value) portion of the declaration.

By this same logic, printTwoDimensions() only accesses known parts of
the Map<String,Map<String,?>>. The compiler should be able to safely
determine that it can accept a Map<String,Map<String,Integer>> since
it never accesses the value of the nested Map.

I don't really need to solve this problem so much as I want to
understand generics better. Do you guys agree that javac "should" be
able to accept a Map<String, Map<String, ANYTHING>> as a param to
printTwoDimensions?  If not why do you disagree.

Thanks, Rob.