[rprasad]

You're right, sweat of the brow is irrelevant, which is why it is irrelevant that their process is now automated. The copyrightable aspects are in the collection, selection, and presentation of data, which is not required by law to be performed manually.

[icebraining]

It's relevant because it requires creativity; it's not automatically ruled out, but it makes it harder to claim.

In any case, Craigslist is completely unoriginal in its selection and arrangement of the data; the selection is "whatever people submit" and the arrangement is LIFO. I find it very hard to believe they'll be awarded copyright over it.