We are not the only people doing book digitization. Others efforts include:
The DIY Book Scanner project is doing very similar work with very similar parts. If you're looking for alternate designs along the same lines, they're the first place to look.
On the blog, John Gilmore nudged us to ask the Internet Archive to release updated software, and James Vasile did so via email. In the mean time, we'll start looking at the old stuff on Sourceforge.
Another Brooklyn-based book scanner developer has a laser cut scanner available with some custom software for page splitting and de-warping.
The Long Now Foundation is developing a software tool to easily convert documents between digital formats.