A short WebmasterWorld thread has one person claiming that his brand new site was indexed solely based on a link from a tweet, via Twitter. He admits he cannot say with 100% certainty that Twitter was the only link to the new site, but he is pretty sure.

I see no reason why Twitter could not be a great place for Google to discover and index new content. We know Google has a deal with Twitter to get their content fast and store it forever. So why not use it for finding new content?

The webmaster said:

Tedster, WebmasterWorld’s administrator said he isn’t surprised. He said:

I agree, since Tweets are often more ‘real-time’ in nature, the tweets likely cannot provide long term, sustained ranking or indexing power that an old aged link on a hub or authority web site in your niche.

Forum discussion at WebmasterWorld.