There is quite a detailed article on visas on arrival on tripadvisor that I stumbled across. It's not straight forward to find using tripadvisor's search since it is drowned out in search results by the many forum posts on the topic.
Vietnam: FAQ Visa on arrival (VOA) - TripAdvisor
We're going in November but with two infants and the thought of us being stuck at SGN for over an hour with little ones means I'm going to get ours from the embassy or hang out a little longer for a change to Visa requirements. Not hopeful of the change happening soon though. The inconsistent information from official sources on VOA tends me to think that this won't happen quickly.