The "cheap trick" part is that the winner is determined by number of page views (which really is a factor of the spamming ability of the contestant) rather than any intrinsic "interesting"-ness of the submissions.
I'm not knocking it, the internet runs on this kind of "cheap trick", and it will generate a ton of traffic and new users. I don't know if it will generate much good will towards Scribd.
The whole point of the site is to post and share documents, which is what this contest is encouraging people to do. In terms of SEO, inbound linking is never irrelevant.
I really love the concept of this contest.. putting all that random crap on your hard drive to good use.
I must admit, I’m a compulsive hoarder of files.. I’m often surprised when I’m browsing through random folders at all the cool stuff I’ve collected over the years and forgotten about.
It's brilliant. Everything from the limitations (real text files that can be indexed) to getting people to link their own stuff from other sites is very well thought-out.
There's a double-incentive for users to get their stuff at the top of Digg, Reddit, etc. First is the MBA they win, and second is the fact that it's _their_ stuff that's getting popular - pure brilliance!
And Scribd's slick licensing clause will make people submit their own, original content under an open source or CC license just for the chance of getting that MBA.