First, I apologize for posting my opinion so late, but I haven't been on the site for a while (and I have lots of reading to catch up). Short answer, for me: yes.
One reason that Pratchett is my favorite fantasy writer is that his fiction is solidly rooted in reality. Conversely, I think it is possible to have non-fiction solidly rooted in wonder. In fact, that's why I also love Chinese author Mo Yan and his hallucinatory realism style. For me, great fantasy is just a fanciful way of telling true stories, and I think it is possible to tell non-fiction in a really wondrous way. A purely non-fiction story with no fantastic elements might be more difficult to pull off here, but I think it has it's place. So long as I go ''wow'' after reading your story, you'll definitely get a +1 from me, no matter how fictive it sounds.
One of the last stories I remember reading on the site was ''Poor Excuse'', which is essentially a non-fantasy kind of story and got a really good score. (And top-scorer ''Loaf Story'' is just one of the best realistic love stories ever written; the protagonists just happen to be loaves of bread. The difference between fiction and non-fiction is often just a matter which words you use; Wonder is absolute). Fantastic elements help in making a story more interesting or memorable, but I think that wonder exists in every good story. And every well-told story has it's place in the Library.