????By Jon Fortt

????Tyrese Gibson’s Mayhem is the first digital book for sale on iTunes 9 – perhaps an early sign of Apple’s (AAPL) desire to take on Amazon’s (AMZN) Kindle and Sony’s (SNE) Reader in the digital book market.

????I would have missed the significance of Mayhem on iTunes if I hadn’t run into Gibson himself on Wednesday. After the Steve Jobs iPod keynote, I spotted the actor/singer known for roles in action movies like Transformers 2 in the demo area where attendees were playing with the new iPods and software. He had a laptop open and was doing a few TV interviews about his Mayhem project, and its debut on iTunes.

????Gibson isn’t the first person you’d expect to make a mark in the comic book business. For one, he’s not a longtime comic book fan – he only recently got interested in the medium while attending the Comic-Con convention to promote the movie Death Race. After seeing the devotion of die-hard fans there, he was determined to get in on the action – and he conceived of Mayhem, a vigilante tale with a diverse cast of characters.

????Take a look at the Mayhem comic iTunes LP ($1.99), and it’s easy to see the potential of book or magazine sales over Apple’s digital store. For starters, Apple has amazing reach – there are more than 100 million iTunes accounts connected to credit cards, which is a sizable audience. In the Mayhem iTunes LP itself there is a beautiful flow to the action; new panels zoom into the foreground as others fade away.

????And it’s not just text and images; both audio and video come along with the package. The interface is designed so that it would obviously work nearly as well on a touch-sensitive tablet – or even on an iPhone – as it does on a full-fledged PC.

????Perhaps that’s because Apple itself had a hand in designing this digital version. While hanging out with Gibson, I also briefly spoke with the two creators of the Mayhem iTunes LP, Sam Herz, one of Apple’s user interface engineers for the iTunes Store, and Barry Munsterteiger, creative director for rich media and Internet technologies.

????The pair said that while working on Mayhem, they created some tools based on standard web technologies like HTML, Javascript and CSS that others might be able to use to create iTunes LPs. But they’ve since turned over their work to higher-ups at Apple, and they’re not sure what will happen to their work.

????They might not know, but we can hope: Though CEO Steve Jobs has publicly talked down the idea of Apple building an e-book, he hasn’t closed the door on a multi-purpose device that does the same thing – something that might look like an oversized iPod touch. Maybe the tools Apple created to digitize Gibson’s Mayhem comic will be part of an author’s kit with that oft-rumored Apple tablet?