Ok. If you create your own control, then if you want to communicate to other module in the same page (i assume the modules ARE in the same page), then you can use javascript code.

For example, if i have modules which called ModuleA and ModuleB and put those modules on the same page. Then in my ModuleA i have a code like this :

<script language="javascript" type="text/javascript">
function ShowMe()
{
    document.getElementById("spanParent").innerHTML = "Test";  
    document.getElementById("spanChild").innerHTML = "Child test";
}
</script>

<input type="button" value="Click" onclick=" ShowMe();" />
<span id="spanParent"></span>

And then in my ModuleB i have a code like this :

<span id="spanChild"></span>

When you put those modules on the same page and click the first button in the moduleA, you will got result on BOTH modules. Because you just communicate using javascript in client-side level. So, when your ModuleA using Ajax to do something, theorically, you just put your code to change some UI in another inside your asynchronous method call in your googlemaps module.

That's my two cents.

CMIIW.