There are also permalinks which could trigger oneboxing:
http://www.openstreetmap.org/?mlat=51.2269&mlon=22.5115#map=16/51.2269/22.5115
This would be a good way to emphasize Discourse’s support of open web. 
OSM is the only real and open alternative to Google Maps we have.
IMO should be supported and whitelisted by default: just like Wikipedia is.