On the original topic, this is a very cool link.
http://astro.unl.edu/naap/motion2/animations/ce_hc.htmlThork, the picture you posted is perfectly explained by a spinning round earth. The center of the rotation axis is just off camera to the left. The closer you get to the right edge, the more the stars seem to simply rotate around a small point (the rotation axis). The further left they seem to curve a bit the other direction, but it's simply based on the perspective of the view due to the very wide field of view.
Rather than one long exposure from a fixed mount, many cameras actually track the stars during the exposure, so that the ground is blurry and the stars are clear, rather than the stars showing trails and the ground staying sharp. In those cases the stars are shown to stay in the same positions relative to each other, and do not move in opposite directions, or at different angles. The time lapse videos posted by The Penguin demonstrate this.