It is frustrating that a Linux-based software e-book reader like FBReader can't run on Linux-based hardware e-book readers. There was a similar thread on FBReader's google group recently:
Does FBReader support Nuut or Cybook ebook devices?. The bottom line is that first there needs to be a SDK (software development kit). So far only the iLiad provides one, and that took a long time to put in place on a device that is much closer to the Linux mainstream than the Sony Reader.