Now this is cool, and I've seen it in demo form for a while:
75 years of BBC programme data, all clickable in a web and ready to browse, search, tags, tag clouds, sparklines of activity. UK TV heaven. No video present but it'll answer all those "who was in X episode of Y" questions (after a little cataloguing and upload delay for recent things).
But there's more! RDF/FOAF descriptions of every show and contributor - an API in plain view as Matt put it. There might be some more RDF format improvements as the focus has been on the web side so far.
Well done Matt and team (Tom, Ben, Julie, Adam, BBC cataloguers, others...)
Tom Coates also gives his launch posting