Mike Cane found a video on Youtube showing what looks like a DIY ereader based on a BeagleBoard. It's running FBReader on a customized version of Linux. The screen is 4.3" (480x272 resolution).
I know it looks like a 1 of a kind kit, but it was actually assembled from commercially available BeagleBoard components. You can even buy this as a kit from the guy who shot the video. Retail is $423.61 (plus shipping).
Nate Hoffelder is the founder and editor of The Digital Reader:
"I've been into reading ebooks since forever, but I only got my first ereader in July 2007. Everything quickly spiraled out of control from there. Before I started this blog in January 2010 I covered ebooks, ebook readers, and digital publishing for about 2 years as a part of MobileRead Forums. It's a great community, and being a member is a joy. But I thought I could make something out of how I covered the news for MobileRead, so I started this blog."