Well, it looks like Yahoo! is indexing a good few thousand pages. Then looking at the pages they’ve actually got Google Page Rank, but the secondary pages aren’t cached.
Google itself says that they’ve got about 108 www.Twitter.com pages indexed buy most are the status links – make sure you link to your twitter.com profile (with no www.)
Just a very quick (2 mins) analysis says that if you can get people to link to your twitter account there is some benefit in terms of the Page Rank passed to the site in the profile. But if you’re trying to get PR to the sites you mention in your Tweets then I wouldn’t bother. The flow of tweets will be too great and move them off your Twitter homepage. If the flow is too low which enables them to remain on your twitter homepage then why would people want to link to you?
So check out your Twitter Bio’s and check to see if you’re using them to their full potential.