The Digital Reader had an interesting article yesterday: Is Amazon Banning Short-Short Fiction From the Kindle Store? - The Digital Reader
From what I've read, only one author was affected. Amazon told her that: "Content that is less than 2,500 words is often disappointing to our customers and does not provide an enjoyable reading experience."
Here's the original thread on KBoard's Writers' Cafe: Amazon going after short shorts
This doesn't bother me; short stories I've ghostwritten for clients for the Kindle are all over 5,000 words. Moreover, I advise clients (and my students) to create collections of stories, rather than publishing one very short story.
Does anyone here have any experience with Amazon targeting authors who are publishing short material (fiction or nonfiction) that's under 2,500 words?