VTap brings live video search to mobile devices. Daren demos a search for "Beet TV" on a Nokia E51, with pretty great results.
The service also offers customized streams of videos that correspond not just to keywords, but combinations of keywords. Daren gives the example of a journalist who set up "Boston venture capital" as his feed. Now anything that corresponds to that combination of terms will turn up on his phone.
Personally, I'm behind on the mobile side. I've had the same phone for years and it can't do anything on the web. But I can see this being useful for on-the-road research, like the journalist example, and for content providers who want to keep tabs on their own vids and be able to share them on demand.