We have used this method of using Scribd in the past. A long time ago, back when Stompernet was good, they told us about this source for traffic. It was well described in getting in there for Traffic, not SEO.
So to officially answer the question, you aren't getting any linkjuice as your links are not detected in the same way as other links.
But if you write about a good topic and put it there, it can be a good source of traffic to your site. Which in the end is what we all want anyhow.
So if you are on the fence. I would suggest, taking articles that you have spun and placing on in there, just make sure it is a good spin. When things are in PDF's they seem to have a little bit more cred, than some crappy content sharing site.
Hope that helps.