brian's blog

From AppleMatters, Dissecting the iPod Shuffle:

The Lithium-based rechargeable battery is encased in silver foil and adhered to the greenboard. Apple notes that the battery (like all Lithium-based rechargeable batteries) degrades over time and will eventually require replacing (see www.apple.com/batteries).

Sounds like the battery won't be easy to replace, if it's even possible. But since the player itself is practically disposable at $99, I doubt people will have the kind of complaints they had about the iPod's battery.