It was hardly the most interesting or earth-shaking part of Jeff Bezos's introduction of the Kindle 2 on Monday, but one small, experimental feature in the device is already causing a minor uproar. Specifically: The Kindle 2's text-to-speech function, which will use a computerized voice to read aloud anything displayed on the device's screen. The problem? The Authors Guild says that that's against the law.

The challenge revolves around audiobooks, which are treated separately from printed material from a copyright standpoint. A retailer can't record a copy of a book on a CD and sell it or bundle it along with a novel without paying a separate fee, just as buying a copy of an audiobook doesn't entitle you to a free copy of the printed version.

Amazon -- and many legal observers -- vehemently question this stance, noting that an automated text-to-speech system isn't the same as a pre-recorded audio book. Some have even compared computerized speech systems like these to reading a children's storybook aloud at bedtime. Since the Kindle doesn't store a copy of the book on the device in an audio format, but rather converts from text on the fly, it seems likely that Amazon is on the right side of the law on this one.

Still, we're in a legal gray area that hasn't really been tested in court, and if our legal history has taught us anything, it's that judges can sway either way on these issues. If the Kindle 2's audio quality is good enough, it could eat substantially into the sales of audiobooks, and that alone tends to be a persuasive argument in the courtroom.

The Authors Guild doesn't seem ready to go to court yet, however. In a memo the organization sent to its membership this morning it said publishers and authors should "consider asking Amazon to disable the audio function on e-books it licenses." Get ready for a long road ahead on this one.