Right, but on the blog post they say they'll offer a few to the community most likely. 100 seems a little excessive for a board test batch, but maybe it was the smallest order number they could get.

100 seems reasonable for QA when you are planning on making >10K right after.

They are auctioning these 100 boards (populated).

Exactly. You might make 10 for your early prototypes but it's not unusual to make 100 or more for the final test run.

No, they are going to populate them all, test them, then sell them.

We’ve made 100 of these betas, which will now be populated with components... Raspberry Pis from this very first, small batch, will be going on sale when they’ve been tested

http://www.raspberrypi.org/archives/389

100 boards doesn't cost all that much more than 10, IIRC.

Populating them takes 10 times as long, if you're doing it by hand. If you're programming a pick-and-place bot and loading up reels of components, that takes time too.

Sure, but nobody said you were going to populate all 100. The point is sometimes simply to have "enough" boards on hand for testing that you don't need to do another run.