I'm not sure whether I'm allowed / supposed to post a response to a Public Value Test by the BBC, but here's what I had to say about the Canvas PVT:
Speaking as someone who is considering starting up companies in this area, I think that this is a fantastic opportunity to create new markets and encourage a new wave of development and innovation in small businesses, in a similar way to how Facebook applications and the iPhone AppStore have created a new wave of companies exploiting those platforms by satisfying user needs.
In particular, the Canvas platform should offer a common payment mechanism so that people can download content and/or applications for the set-top box in a manner as simple as buying an application on the iTunes AppStore on an iPhone. eg you could pay 50p and get a great little TV-based application for seeing ski conditions on your favourite slopes, or a game, or an interactive TV-watching tool, etc. Either the Canvas JV itself could manage the payment interactions, or it could create a payment standard that is handled by the ISPs providing the broadband connections (users already have a financial relationship so this would be easy to manage, and would give ISPs a new revenue stream by taking a percentage of the fees paid).
Another area where innovation would be key is the EPG -- the Canvas system should allow for "pluggable EPGs" so people could choose to change their EPG, possibly using the payment model described above to purchase an EPG that exists in a 3D world, or whatever crazy ideas people think up!
BBC Backstage has taught us that without a commercial incentive, people building tools for BBC services are limited to hobbyists and dabblers, and user needs are not met in any mainstream way. Introduce a potential revenue model, and innovation flourishes. Canvas is a perfect opportunity to make this happen.
A thriving Canvas ecosystem could also encourage other countries to adopt the Canvas standards, giving the UK a lead in an important new market around the world.
[Also added in response to their questions about draft market analysis]
I don't believe that "freesat and freesat from skypenetration remain broadly constant" (annex 188.8.131.52 p28), wouldn't they switch over to Canvas Freesat?
You only seem to have covered threats/substitutes from pay-TV providers, what about Microsoft/XBox 360, Apple TV, IP-only boxes like Roku and Boxee using internet services such as the Netflix API in the US? They are already growing rapidly. Also of course there are the TVs with direct internet connections, most of which are coming out of Asia working with the US, eg embedded YouTube. If the UK doesn't respond to this emerging market, people may end up watching more US-originated YouTube content (much of it of dubious legal standing) rather than UK-originated services.
The radio market may be affected when people can use IP-connected TVs to listen to radio from around the world, or services such as Last.fm or Spotify through their TVs in surround sound etc. This is negative for incumbent radio stations but a huge opportunity in general.