To get qualified one has to show proof of community participation, references, mashup projects worked on and finally appear for a online exam.
My Google Mapping journey started with Hurricane Katrina, way back in late 2005. My first mashup was showing where businesses were opening up in the New Orleans area once Hurricane Katrina was gone. Check out the blog post on my 1st mashup at GoogleMapsMania. (Note: The link (weshallrise.org) in the blog post no longer exists as I cancelled it after couple of years.) Since then I have created numerous mashups which you can check out at this site.