That's probably the best way to do it, building piece by piece, I mean. I checked out your video and it's cool, but it has its limited usages (peer to peer micropayments is a freaking cool thing). Does it work or can it be adopted for things like public WiFi usage?
It's a general framework. Yes, paying for wifi access is possible (more possible than you might imagine).
How would you accomplish the proof of storage challenge if the original author of the data isn't available online to challenge (or the user loses his metadata required to produce those challenges)?
If the challenge metadata is stored in the same place as the micropayment channels, you either lose both or neither. I think that's solvable. The challenges don't have to be big. If you want 1000 days worth of storage, store 1000 80-bit hashes and you're done, right? 10kb of data is trivial.
Is your TradeNet talk available somewhere?
Yep, see the top video and slide deck beneath it here:
http://plan99.net/~mike/(unfortunately, the slides in the video are hard to see and washed out)