I finally got around to netflixing Planet Earth. Wow. What great stuff to watch with the family.
Great white sharks jumping out of the water and eating seals like trout jumping for bugs.
Anyway, in the opening scene of the first planet earth they do a sunrise to sunset time lapse of an ethereal, cloudy, mountainous horizon WHILE the camera pans across the mountain range.
How in the $%@! did they do that?

No telling how they did it, but this is what I use for single or dual axis moves during time-lapse work using a DSLR. A telescope control unit.

Here is a look.

They use motion control, some of the systems are quite simple just a powered head that can pan and tilt, others are more complex. On an earlier series they did a year-long time-lapse that also tracked-in, awesome shot, but I wouldn't want to pay the rental on the kit - oh hang on, I did, as did every license payer in the UK...

There is a shot like this in "Requiem For A Dream." It's highlighted on the "Anatomy of a Scene" special feature on the DVD.

Here is the thread showing my dual axis Time-lapse rig.

http://www.dvinfo.net/conf/showthread.php?t=106477