I downloaded a really nice Google Maps Intellisense helper.
To make use of this intellisense at the page level you can add a script reference in the HEAD of the page:
<%-- GMAPJSHelper assists in Google Maps Intellisense --%> <script type="text/javascript" src="scripts/GMAPJS/GMAPJSHelper_Release.js"></script>
This works with all JS libs including the SilverLight one.