A couple of rumours are going around suggesting that big caches of formerly lost BBC material have been found. There's meant to be a new Beatles live sessions album coming out in November, and supposedly there's evidence that old Doctor Who episodes are being aired in the Autumn too.
Hopes for other lost material being uncovered? I'd love to see the Scott Walker TV series. There's only a few little bits of audio of it publicly available right now as opposed to the six or eight episodes half hour episodes that were filmed.