What's the white grid thing in the upper-left?

I've only noticed it over my logging camp and police station, but it could be over others. I can't figure out what it means.

I haven't noticed it changing any, but I haven't paid much attention to it. Does it have some meaning that I'm not getting?

That just means that currently there's an overlay of some kind that is active, for instance, if you go to the overlays menu on the bottom left and click on any of them, the graphic will change into that. The reason why its active when you click on logging camp and police station is because for the logging camp, the wood overlay is showing (telling you where is a good spot to place it) and the police overlay shows the crime rate.