There's been a lot of discussion of this issue on the large format photography forum, and there seems some agreement that the Camera Work type of look comes from the printing methods as much as anything else. Ortho films, pictorial lenses, contact prints from more primitive methods like bromoil, gum, or similar printing all contribute.
Many of the older print methods require a contrastier negative, as xray film delivers. I'm messing with simple soft focus lenses and xray film, myself, trying to replicate an early 1900s portrait/pictorial look. Examples are most of the things here, down to the fence photo:
http://flickr.com/michaeldarnton A friend suggested toning would add to the look, so I've been doing that, too.
The most recent one, the Spinner, seems most successful to me so far. Ultimately, I hope to be doing carbon printing. I'm looking for a really retro look, basically, without going full blast to ambrotypes, which seem like too much work.