Heard nothing and found nothing except confirmation that it assumes the car was parked at the moment it disconnects Bluetooth from a car. There seems to be no way for our apps to detect this, unless it's tied in with "visits" below.
My app does keep a map on screen, maybe it could look for a parked car annotation on it. Haven't tried it and it seems messy.
I have been looking at an app named EverDrive, which magically detects your driving habits and scores you based on things like speeding, heavy braking/acceleration, sharp turns etc., with no connection to the car. It seems to do it just based on location manager reports on speed and such.
There is also something the system calls "visits", and you can get notification when a visit starts and ends. It's not super clear what deliniates a visit, but if you get out of your car and go into a shop, then go home, that time in the shop generally gets registered as a visit. But I don't seem to be able to use a visit start notification for parking, because by the time I get it, the person has moved away from the car and it's too late to get a location fix. Also I'm not sure about its reliability. Visits are a bit mysterious to me, but they may be or someday become the answer.