Explanation
Mapbuilder can be used to put Google Maps (both API version 2 and 3) in a web page. Do not forget to load the google script with your API key though at API version 2.It requires the use of OwsContext instead of a normal WMC context. For more information have a look at the wiki
You can use Google, or Yahoo/MS for that matter, as a baselayer for your application. The best approach is to use the epsg:900913 projection, but that does require that your mapservers support that projection. Alternatively you can use epsg:4326 but it has a tendency to deform at larger resolutions.
