You can find markerwithlabel.js on github
https://github.com/googlemaps/v3-utility-library
under the subdir you can find all the googlemaps-v3-utilities you need
the old http://google-maps-utility-library-v3.googlecode.com/svn/tags/markerwithlabel/1.1.9/src/markerwithlabel.js seems no longer supported ..
