Interesting. I'm re-building the core engine powering this using (basically all Javascript right now on Backbone) in Ruby + Javascript with an actual postgresql database behind it. Right now it's using an in memory store for things like your autosave drafts etc.
Do you think I should open source the project? Right now the Android app and the web-app (mentioned above) are closed source, but the philosophy of this platform is about open source writing - and to not have an open source application powering that seems antithetical. What do you think?
I would say it depends on your personal goals. If you're doing this as you say to open source wiring and not the application then there's your answer. If you'd like to see it develop more than you have time for theb maybe open source would be a better option or talk to some friends that find it interesting and build it together white keeping it closed. So weigh your options and what you'd like to see happen to it and go from there.
Open source would be great! Sounds like you've already got some prospective contributors out there, and an open source project will naturally be easier to market to GitHub users.