Not hearing it
I don't really see the point of this recently released software to read your email and docs into MP3s so you can listen to them on your iPod. Even if the text-to-speech is good (and some of it does work well), it just doesn't fit with the way most people work with their email - you read it and give a quick reply. It isn't a novel that you want to take time and be entertained by, but something you usually jot off a reply as quickly as you can (hence the popularity of Blackberry). If you want to talk, why not use the phone?