Here's an idea: If people could wrap quotes in some tag like [qfeed]a good quote[/qfeed] in media outlets all over the internet, like Disqus comments for a particular blog or in reply to the quoted post on HN.

And then a spider came along and pulled the [qfeed] bit and submitted it to quote-feed.

It wouldn't work well for comment-less sites like wikipedia, but it would for "quick excerpts from the latest articles"