Most of its members don't use MySpace as a promotion tool; they're just there for the friends. But MySpace can be a foolproof self-promotional tool if you're intent on using it that way. Any author, even one without computer skills, can easily post photos along with artwork and sample text from their books. You can include links to buy your book from online retailers, publish a MySpace blog, and send bulletins about your public appearances and publication dates.
Big publishers have noticed the potential for publicity on MySpace, too, and have been building profiles for their authors, often using the same canned material from press releases. Readers who are already fans might be interested in this warmed-over stuff, but authors building an audience must get involved. You can't fake participation online for very long.
In addition to its networking opportunities, MySpace is a wickedly good research tool. For example, in about 10 seconds you can find out how many members say "Malcolm Gladwell" is their favorite author, and you can zap a message to them if you like. Or you can quickly locate members in your ZIP code who are science-fiction buffs. Authors can even use MySpace to figure out what books their own friends and fans are currently reading.