My startup? No, just something I came across two weeks ago. Actually, I was a bit surprised it hadn't been submitted yet.
I visited summize.com before. They used to focus on searching book/movie reviews. Now it is totally different.
Yes, I remember that. It was innovative and very useful actually. The new twitter-summize seems not that impressive, not ground breaking at all, and far less useful. Plus we already have tweetscan.com.
Is twitter search that important? I think the value of twitter is in the instant, not in the history.
The rss feed to subscribe to a search is useful. I want to know when people talk about my company on Twitter, so I subscribe to the search results for some Flaptor-related queries on our Twitter Search. I don't care so much for what was said a week ago, only about the new results.
Summize picks up more results than Tweetscan, at least in my experience. I'm not sure why.