The BBC produced a five-part documentary called The Genius of Design. It's absolutely fantastic and is currently airing in the US on The Smithsonian Channel. As with lots of BBC content, they're trying their hardest to prevent it from being seen online because... I don't really know why.
I found all five parts online here. It's a Chinese website and as such takes forever to load the videos. You can also go to Isohunt.com and download a torrent for both it and the producers previous series, The Genius of Photography.
It is easily the best television retrospective on design ever produced. It's thorough, detailed, wonderfully shot, and managed to straddle the line between design porn and legitimately informative.