Interesting this thread came up. My 4th generation iPod touch recently had its battery nearly completely give outstill useful for some things when near a power source, and it's just out of warranty (should have gotten AppleCare on Amazon or eBay).
Anyhow, I just picked up a 32 GB refurb iPod touch 4th generation from Apple to replace it, but its battery life seems worse than my original 4th generation's battery life was when it was new. I started thinking about returning it and buying a 5th generation new (for about $100 more) or even the 64 GB for $365 on Amazon.
But of course Apple may update in September. Still that is a bit of a ways off given I use my iPod touch every day.
Can anyone give a battery comparison between the 4th and 5th generation iPod touch? That's one of the most important aspects for me. The ability to run iOS 7 is slightly interesting to me but not a dealbreaker or I wouldn't have bought the refurb. But spending the extra money, it would be nice if it ran iOS 7 well.