Apple's figures for the battery life on a iPod are misleading, disingenuous, or at least economical with the truth. For a fifth generation, 30G iPod, they say 14 hours music playing time on a fully charged batter. If you think you are getting less than this, you can run a test using a methodology listed here. Basically, you set your iPod to play a single album on repeat, with the backlight and EQ turned off. Repeating the same album means there is little or no disk access, and turning off EQ reduces extra computation. If you get less than half the specified time, you can consider the battery faulty.
So another way of putting this is that the battery life is between 7 and 14 hours, provided you are using the iPod in completely unrealistic way. If you ever use the backlight, shuffle the playing order, or skip tracks, you get far less.
On the test, my iPod gave 11 hours and 10 minutes, about the in the middle of the range. In my typical use, with no EQ and the backlight timer set to 5 seconds, I get between 3 and 4 hours, which is barely acceptable.
Apple like to present themselves as a white knight: we are good for our users and morally better than the other guys. Well, they've always been better at projecting an image than creating a reality. This is the company who forced the one-button mouse on us, or made out that a Mac was better because it had a case made of translucent blue plastic, and who are currently advertising themselves as better than Microsoft by means of sneering at them. I think I would rather they put their efforts into being more honest about themselves.