I have had a play with this recently at my weekend place recording an SQM of 20.92 which I believe is pretty good. ( no street lights for 25 km) Once measured you can then submit into the cloud for someone presumably to pick up and analyse.
Just for larks on admiring the "Super" moon in Sydney I took another measurement (through a reasonable sized gap in clouds) and recorded 17.95
Checking t'interweb I came across this article which lines up with what was measured quite well.
http://www.skyandtelescope.com/astro...-your-skyglow/
Neat little app. Also has results from other users as well.
Clear ( and less bright) skies..