I like your chart, Railroadmaster. The second chart posted is also useful but too "busy" and mostly intended to show Tizen's detailed history.

Probably it would be a pain to do this, but what I'd like in the chart is thick lines and thin lines roughly indicating relative contribution of the upstream osses. Also, maybe stick in Harmattan downstream of MeeGo.

Very interesting, I didn't realize Blackberry had any relation to Symbian.