The latest beta from Google labs: Google Video Search.
According to the About page it works by indexing the closed captioning text that’s broadcast with the shows. You can’t actually see the video though, just an accompanying still image.
C-SPAN is a partner in this; it’s a good fit. I can see this being very useful for researching public affairs information.
UPDATE: This NY Times article (via Instapundit) has more information. It also notes that Yahoo will soon be doing something similar (in addition to their existing web-video-clip search.) Good. It’s nice to see a little real competition again among search engines.