I'd be very interested in hearing if someone from Flow could talk a bit about their client-side code. It appears to meld Backbone.js with Socket.IO, for live updates to models via remote collaboration...
Glad someone asked that question, was thinking I'd get to the bottom and have nothing but pointless discussion on 10 bucks being worth it or not.
I'm looking forward to writing a bunch about that. I'll be drafting a series of blog posts over the next little while that will cover our choices, problems, and experience developing the app so far--and, more importantly, going forward.