PubSub. Rather interesting new RSS search service.

‘PubSub finds new content as it appears on the internet. Then we deliver that content to anyone who’s expressed an interest in it…PubSub operates by first storing your subscription query, and then watching for new information that matches it. Your query will be checked against every piece of new information passing through our Matching Engine.Today, PubSub reads over 2 million weblogs, more than 50,000 internet newsgroups and all SEC (EDGAR) filings. In the coming months, we’ll be adding many more streams of data, so stay tuned!’