I think 100m is the best they can guarantee. You may get better results based on the data they have in your area (especially WiFi triangulation), but it's not guaranteed. In any case, the best they have for me is: http://imgur.com/vVbqSvr which is coarse enough to not actually provide much data. I could have been to any one of a dozen or so businesses in that area.

We all know it was Tim Hortons.

This is by far one of the creepiest things I've seen.

Also one of the most useful.

Funny thing though - Google could easily blow all those Endomondo et al. "share my running" apps out of the water by just allowing to publicly share a time-delimited subset of your location history...