Since you offered... I'm curious about the rendering technology behind it. I'm working on a web app with a spreadsheet interface, and I'm using a standard canvas-rendered grid.
You obviously have different design constraints, so it would be interesting to see how they shaped your solution.
You didn't ask a specific question, but it basically comes down to getting really good at calculating layout fast, getting good at figuring out how to incrementally maintain your rendered view, then getting really good at figuring out how to optimally use the hardware you're targeting.
We do not yet support editing print layout, so you can't adjust the pagination / change the page size in / with Nobie yet, but that will come soon :)