As is a common practice for highly-anticipated titles, Dark Souls will be given a Collector’s Edition boxset at the same retail price, but with plenty of additional content that makes it worth the effort to get.
The content in the Collector’s Edition includes the game itself, which is self-explanatory. It also includes the original soundtrack to the game, which is always an excellent thing to have in my opinion. A game guide, behind-the-scenes videos, and two artbooks, one of them a hardback, showing off concept art for the title. This all comes in a unique metal case.
This being the same price as the normal game, this is likely going to be in extremely limited supply. If you want this, you’d better preorder it. I see a few nice Collectors Editions at a slightly higher price, but I’ve not seen many go for the retail price of the same game. This is an excellent incentive to preordering the game as opposed to some crappy DLC content that can probably be cheated in.