Yes, I did see one in the parking lot of the Audi Marketing Research center in Agoura Hills, which is 20 minutes from LA (to think I forgot my camcorder, too). It was a blue-grey A8 with platinum interior. One word, WOW! Especially when there was a Benz S-Class next to it. The A8 is to darn athletic, like Michael Clark Duncan in a tuxedo. Here's a run down of the "extra" features on the car that I was able to spot right away:

3-spoke steering wheels (looks absolutely great!)
finger-print scanner (yes, I finally saw how it looks like)
Advance-key entry system

Unfortunately, I had to meet a business partner/client in the area for lunch, and when I came back the car was gone.
So I went to the office of the marketing division and found out that they run different tests in an around the area. They had 4 A8/A8L tested, including this one. The one I saw was used to test the Navigation system. In fact, someone from Germany Audi was stationed there for a while. They even had the Touraeg and the Phaeton tested there. Too bad I didn't see it. Across the street was the techical center for VW and Audi, but that was sectioned off.

All in all, it was a great day and I got to know some of the marketing head guys in that office, who shares the same passion for great cars like we do in this forum. He even said, next time when I'm around the area again and the A8 is in the area, I can take a look at the car again =)