I left my iPod Shuffle in my car all day today, connected to my car stereo and playing (although the car stereo itself was off of course). It still had enough power to provide me with music all the way home, which means it lasted at least 8 hours (it wasn’t fully charged this morning).
I’m currently listening to iTunes on my PowerBook, and it is using between 10 and 15% CPU. This obviously runs down the battery in my PowerBook.
Why can’t Apple “build” an iPod shuffle into the PowerBook? It could connect to the USB bus internally, and all it would need is a kernel driver to control it, that iTunes could use to tell it to play a particular track. It would free up the system CPU to do other stuff, and extend the life of the battery.