Some time in the summer of 2010, Google changed their policy regarding how they treat Twitter.
Twitter is a very fast-paced micro-blogging website. A quick search on Google for the number of tweets posted every day returns some amazing numbers: around 1.9 Million! That's a lot of 140 character messages and we'd guess that's 44.3 Million words posted per day.
Another quick Google search for the average number of words in a book and we find different experts saying between 70,731 and 75,000, so let's take 72,865. Using that number, we estimate approximately and equivalent to 608 books (novels) worth of information is posted to Twitter every day.
Interwoven in all those "books" are millions of links to other websites. Some of the links are pure spam, and some are really good links to worthwhile information. That's a lot of valuable link information for Google to simply ignore, so they had to change.
The nofollow attribute is applied to all the links on Twitter, so it would seem that Google ignores all those links. But they don't any more. As of the summer 2010, they get a direct feed from Twitter of all those tweets, but without the nofollowed links.
The bottom line for today's Nugget is to start using Twitter because it's valuable for SEO. Make sure any well rounded link building campaign is using Twitter to link to all your internet properties. Don't always focus your linking to your main website, instead link to your blog, a product page, your Facebook account, etc.
Be creative with your Twitter linking.