MobileMag reported that PortalPlayer announced the PP5022 System-on-Chip that some analysts believe will power the fifth generation iPod. The big news in this release is a large projected increase in battery life. According to the article:

The PP5022 is specifically designed for enhanced features on hard-disk drive-based personal media players... and offers triple the battery life of the PP5020. With the PP5022 chip, a 5G iPod would give you an estimated 36 hours playback, the iPod Photo around 45 hours, and the iPod Mini around 54 hours. This is a huge jump in battery life....

Apple just started shipping the fourth generation iPods, so I can't agree with Peter Rojas' recommendation to wait until the fifth generation iPods are released before buying. The just-released iPod Photo has an estimated battery life of "up to 15 hours" for music playback. That's considerably better than the battery life of my wife's second generation iPod.

Every time an electronic component comes out that holds the potential to dramatically improve the performance of an existing product, you have to ask yourself, what's the opportunity cost of waiting until the beginning of the next product cycle to purchase something I want today? The cost of a 30-Gigabyte iPod Photo is $349. If you used it for the next eight months then threw it away, your cost would be approximately $1.45 per day.

Having my own iPod would definitely be worth $1.45 a day to me, and docking it to my blogging workstation overnight doesn't represent a personal hardship. This is how I would justify a new iPod purchase at this point.