Google Real Time Search and Tweets

Amit Singhal, a Google Fellow, who led development of real-time search has come out with some points re how Google rank Tweets.
Google rolled out a real time search update in Dec 09 to better incorporate breaking news. Twitter is a small part of this world
and it seems Google is ranking Tweets in a similar way to the Page Rank links model. So trust and reputation works here, you earn and give reputation.
The more people that link to you [follow you] the more trust you have and the chain goes on, sound familiar?
Interesting to see he states that hashtags can be a redflag to low quality tweets and spam, hashtags can be useful in group conversation.
More on this post can found here; http://www.technologyreview.com/web/24353/page1/