Interesting thread; I was going to try building gphoto2 myself. Though it seems like it could be rewritten way smaller with less libraries with a bit (a lot..) of effort.

I use gphoto2 with my Kodak; AFAIK the camera does not support capture. I've never found a list of what cameras do.
My daughter's (newer) camera can be set to either gphoto mode or USB memory mode; I presume the N810 would be able to read it in memory mode.