I actually flipped my car similarly to the way the OP did, with four differences:

1. I didn't have any animals to blame, just a brief moment of inattentiveness and a millimeter-or-two-too-sharp jerk of the wheel when I first felt one of my wheels go out of the lane. At the time I still could have fixed everything if it wasn't for that instinctive wheel jerk.

2. I flipped around 2 times, and then the car rolled about a fourth of a rotation back the way it had come from - presumably because momentum first carried it into a position beyond where I first was (best as I could count from memory and from the end-result position), and not in a fully around-the-front-to-back axis, but in a spirally way, because of how the car hit the guard rail before flipping, and was facing the direction I had been coming from by the time it stopped.

3. Came to rest on the side, not right-side up. Doors were locked, and the unlocking mechanism (both manual and electronic) got jammed, so I kicked my way out through the front window.

4. I did not own an N900 then. However, the phone I had at the time went flying from the car, much like the owner's. It was daytime, I I eventually managed to find it by walking around long enough. Luckily for me it was in the area, and wasn't catapulted across the highway, so I didn't have to cross any traffic. Screen got scratched up, but I was able to scratch off the protruding parts myself later, so it returned to being smooth as hell to the touch, just with visible scratches, which I didn't mind. Phone lasted just fine until I got my N900 and, months later (as program availability for it skyrocketed), finally decided it was ready to be my phone replacement.

But at the same time, my N900 has taken some decent falls onto hard stone tile and once on concrete. Luckily the screen is safe; the concrete fall scratches the back cover on the corners, but other than that it's fine. The worst I've had is needing a reboot when the accelerometer got stuck with one value biased by about a thousand in one direction. Reboot fixed it each time, so obviously the hardware survived just fine.

- Edit -

kaos_king: If you don't remember that day, and getting drunk isn't like you, I'd be very suspicious of the possibility that your friends, or other acquaintances, did something very stupid or asinine (probably without themselves imagining what the consequences would/could be), which led to your injury, and then decided to cover for each other by giving you the you-got-drunk-and-climbed-on-a-wall-then-fell story.

If you trust everyone enough to be sure that's not the case, of course, I don't want to encourage paranoia. But it's a real enough possibility, I think, to deserve mentioning.