E-book readers are no longer safe from spam. Amazon's self-publishing service for the Kindle has become the first major target.

Reuters reports that spam has taken form on the self-publishing platform for several factors--namely how cheap and easy it is to republish another work already available, or to just make something else up altogether:

Aspiring spammers can even buy a DVD box set called Autopilot Kindle Cash that claims to teach people how to publish 10 to 20 new Kindle books a day without writing a word.

The news isn't all that surprising. ZDNet discovered Kindle spam in April after David Chernicoff highlighted the issue after downloading a bogus book. At the time, Amazon removed all books by the author, but the approach seemed to be a one-off. Obviously, Amazon needs a wider crackdown.

Paul Wolfe, an Internet marketing specialist, told Reuters that Kindle spam has bloomed exponentially in the last six months:

So far, it looks like Amazon's only significant attempt to dissuade spamming was the launch of Kindle Singles, which is for shorter pieces in general. But that isn't enough.

Amazon needs to be more vigilant and have a stronger system for weeding the spammers out. If they don't, not only is Amazon going to lose a lot of authentic self-publishers and writers who don't want to see their work plagiarized and manipulated, but customers are going to be the first to go after they repeatedly stumble on spam when looking through an eBookstore.

It doesn't look like any other digital bookstores, such as Google eBooks or Barnes & Noble's eBookstore, have been hit by spam yet. But this should serve as a wake-up call.

UPDATE: There's somewhat of a stir about the Autopilot Kindle program. Autopilot's developers and fans have written a response, which can be read here.

This story was originally posted at ZDNet's Between the Lines.