I've been playing with the Sony Librie e-book recently. I got it from here. It runs Linux, and someone patched the root image to be in English. Also added was the ability to run arbitrary code off of a memory stick.

We're going to use the Librie in a study, so I hacked up some code to display arbitray images on it via USB. Here's the stuff:

librie.tar.gz Includes:

• source: pgmto4bit.c
  binary (i386): pgmto4bit
  Transforms a headerless PGM file into something that can be displayed on the Librie (4 bit image).
• source: send_pic.c
  binary (i386): send_pic
  Sends an image created with pgmto4bit to the Librie over USB.
• source: rec_pic.c; usbtg_pd.h; librofb.h
  binary (arm): rec_pic
  Runs on the Librie; receives and displays the image.
• script: lbhook.sh
  Put on a memory stick, kills the Librie software and runs rec_pic.
• image: stuff.4bm
  “screenshot”: output.jpg
  Test image for sending to Librie

The above will only work if you've converted your Librie to English and can run stuff (e.g., the root console hack) off of a memory stick. This means you'll have to have the USB module from the console hack loaded and working as well.

See my delicious bookmarks for links to various useful things including the root console thing.