Raindance, a wonderful screenwriting resource, has posted the 2011 Oscar nominated screenplays for both original screenplay and adapted screenplay.  You can download them in PDF form from their website here: http://www.raindance.org/site/index.php?aid=7122

So, what is the difference between the two categories ‘Best Writing, Screenplay Written Directly for the Screen’ and ‘Best Writing, Screenplay Based on Material Previously Produced or Published’? Simply put, the former is a script that was written purely from the screenwriter’s or screenwriters’ imagination, and is original source material that has not be taken from any other previously written materials and mediums, while the latter tends to be an adaptation of another published work, such as a novel (i.e. ‘Winter’s Bone’) or comic book, or is based on a true story (such as ‘The Social Network’ or ’127 Hours’).

The nominated 2010 screenplays can be found on the Raindance site here:  http://www.raindance.org/site/index.php?id=474,5334,0,0,1,0