This is actually well-known for years. Any flight ticket you charge to the Citi PremierPass card (even just a few dollars in award taxes/fees) will earn you the full amount of flight points per the distance of the flights, which can later on be matched 1-1 with purchase points (so, 2 points total per miles flown, if you have the purchase points to match).

I seem to remember seeing some card changes, and I think the Citi PP cards may be going away. I don't see any mention of flight points on the web site anymore.