Openmoko's WikiReader, a popular palm-sized touchscreen electronic encyclopedia which contains more than 3 million English language Wikipedia articles, now can be turned into the world's most portable eReader able to display the contents of Project Gutenberg, the oldest digital library. Its more than 33,000 digital books can now be downloaded and added to the WikiReader by visiting http://www.thewikireader.com/update/.
The WikiReader is a handheld grayscale ereader that was designed to hold the entire contents on Wikipedia. I have one, and aside from the lack of pictures it's quite nice.
Note that if you want to use this update, you'll need to download the full multi-GB download all at once. Also, if you want to keep the Wikipedia files, you'll need to upgrade your microSD card t0 16GB.
That download issue is the one serious defect in the design. At one point I looked into making ebooks for the WikiReader and I gave up. The problem is that you have to gather all the source content before you can generate 1 file. If you wanted to do this PG update on your own, you'd need to go get all however many GB of files before you could even start.
With other platforms, you can just make an ebook and add it. It doesn't work that way with the WikiReader.