I know I'm repeating myself, but this is really, really nice work.
Keep in mind that this will be the foundation for extensive future improvements, so we don't need to have everything included immediately.

I'd be ecstatic with even a basic nonproprietary reflash package. Everything else is a bonus. There's a whole
roadmap with lists of future improvements.
I updated the roadmap in Trac with new goal dates. The dates are a little arbitrary and highly ambitious (unrealistic?): at this point, the next milestone (2.13) is due is 2 weeks, with new milestones coming every 2 weeks after that. Adam, what do you think is a reasonable date for a finished 2.13? I assume you'll release a beta first and then we'll test it and tweak it.
Looking at Trac, there's one potential issue I haven't seen mentioned: it looks like the current on-screen keyboard is proprietary and needs to be replaced with the matchbox keyboard? Is that correct?
Edit: Or, if the mobipocket software copy-and-restore script works, we could use that for the keyboard as well. That would probably be the best workaround.