It looks like a re-run of the iPOD's dirty secret saga which resulted in a class action suit settlement . According to some unlucky purchasers, the Nano screen is prone to scratches and damages. One Nano owner has set-up a website to share his story (warning: some readers may find some damaged products' pictures upsetting) and check whether other Nano customers encountered similar problems. Apple's Nano discussion forum is buzzing with such conversations.
Steve Rubel published a Blogpulse's graph illustrating the increase in blog postings mentioning the problem and The Register ran a story on it.
UPDATED: Apple's response, courtesy of an anonymous reader.