Originally posted by poet1b
With the direction of the trajectory going across the scene of view from which the photos were taken, it the rocket began to spin out of control in space without atmospheric resistance, it still should have continued on its course, and we should be seeing a corkscrew, and not a perfect spiral.
Actually, if you mean that the "rings" in the left side of the spiral (as viewed from Norway) should be compressed (as I was thinking for a while - as it just seems intuitive) while the right side would be expanded (as shown in the side view of the first simulation on YouTube, as well as this additional simulation), since the object is in motion and there is little significant acceleration (or deceleration) throughout it's trajectory, the left and right sides of the spiral will be travelling along at about the same velocity as the object (minus the difference in velocity due to being expelled from the object). (Hopefully this description makes sense - the main thing that allows the spiral to look mostly circular is the lack of acceleration/deceleration in the object.)
Just for illustration, the circle I created in the image below is centered where the object is at the center of the spiral - this makes it much easier to see what kind of an effect atmospheric drag has on the exhaust from the object:

If anyone's interested, I have put together a total of 381 images from the Norway spiral, the recent event in China (though there are only 4 images of that - all linked from this thread), and past events in China and Russia (the latter is in the 'misc' directory) in this file:
norway spiral.zip (30.6 MB)
Also, using the names of the photographers and an online Norwegian phone book I put together this file for Google Earth that has the approximate locations for 50 people (with a few that are exact/verified) who have taken pictures of the spiral (their pictures with their names added to the filenames are in the previous zip file). (Note that there's only one Dagfinn Rapp in the phone book which places him in Southern Norway, but this page states where he was to take the picture he took so I put in both locations; similarly, I put in Karen Elisabeth Hough Bjørndalen's home address and the GPS location from the picture taken with her iPhone 3G):
norway spiral - google earth.zip
Lastly, poet1b, since you were asking about the exposure time and lens used for some of the pictures, the only two pictures I've found that have Exif information are Karen's (on her blog, linked above), and this one taken by Jan Petter Jørgensen. I don't have the space to post all the Exif info from Jan Petter's picture, but the exposure was for 1 second exactly and the focal length was 41 mm (times 1.576 [35 divided by 22.2] gives you a 35 mm equivalent focal length of 64.6 mm). If you put 41 and 1.576 (under 'Digital multiplier', since the camera's sensor is smaller than 35 mm film) into the calculator on this page you can get the width and height of the field of view in degrees. This page has the 35 mm equivalent focal length for the iPhone 3GS camera so you can compare the size of the spiral in the two pictures. (I haven't done so.)




