The 'spat' broke out on the OGC Mailing list, here's the May Archive: http://lists.osgeo.org/pipermail/discuss/2013-May/ There are about 100 messages about it on there.

There's also this Open Letter: http://wiki.osgeo.org/wiki/Geoservices_REST_API#Open_Letter_...

And James Fee's view on the whole thing: http://spatiallyadjusted.com/2013/05/09/esri-and-an-ogc-stan...