Thanks for mentioning that - Have to say, it's a work in progress. The query language for JSON (called SpahQL) is done, but I'm currently working on the document runner. See the readme for how it's meant to turn out.
Don't have time atm to read it too in-depth, but it seems like this is a bit different from what I was thinking of, in that I was thinking of a more complete rails-like MVC type thing. But it does seem to confirm that I am in fact not retarded, and that this type of thing is a good idea.
Sure - Spah is intended to act as the V in your MVC. I'd probably just use Express for the C and Mongoose or similar for the M.
I find that stitching my own framework from quality open source components gives me a bit more flexibility than Rails (rails user since version 0.7) and lets me get closer to the metal when I need it. Your mileage may vary :)
Okay but so there may be, for example, duplication as far as your model code? Like, I need to define my model through Spah, but then I also need to define the same model in my server side code that's going to be serving you that data?
I was thinking of something where you essentially write the whole app in ruby, and then it generates DataMapper models for your objects, sinatra routes to access the data, and js code to actually access the server and hook it up with your ui. Something more along those lines.
I first touched rails at 2.something, a bit before 3.0, but it was my first experience with MVC (that is, a single framework that handles all of your MVC) and I had a lot of mixed feelings about it. I still bounce around a lot but right now I'm leaning more towards "MVC is good".