On my week-long journey to "figure out" Twitter, I've also been doing a bunch of reading on other SEO sites to see what they have to say about it. By far, the most hilarious post I've come by is this post at SEOMoz. It's sarcastic - at least I hope and think it is - talking about how the SEO community has simply run-away with the idea that Twitter carries some super secret search engine ranking juice.
I guess there has been a bunch of debate on SEOMoz about social media, and Twitter in general. I was somewhat relieved to see the author of this post (later promoted to a YouMoz entry) describe Twitter as an "endless stream of garbage." Not because I don't want to believe in Twitter marketing, but because I've basically found so much of what I've read in Twitter to be low-quality. Sure, the occasional helpful post swims along. But there is a ton of junk also.
So the SEOMoz post basically says (in case you don't want to read it) that the people thinking that Twitter will somehow carry some super secret link juice are out of their minds. They further point out that the site is not nearly big enough or powerful enough to impact the search engine rankings in any significant fashion. This does not mean that the idea of very soft marketing through Twitter is not valid. Just recognize that you are not likely to get any search engine ranking advantage from your activities.