This is huge, and it's likely that Apple will enable this for themselves in an iOS update at some point. I can't count how many times I've browsed video on my laptop with others around only to wish I could throw it onto my TV.
The more I think about it, could we have a future where TVs don't have inputs? They would be simple streaming clients to which other devices push content. You've got your phone with you - why would you need anything else?