In Our Post-PC Era, Apple's Device Model Beats the PC Way
The Wall Street Journal

Critics attack the iPod and iTunes as 'closed' and 'proprietary,' because the songs Apple sells at its iTunes Music Store play only on iPods, and iPods can't play songs purchased from other music stores. But both the iPod and iTunes handle the two most common open audio formats, MP3 and WAV, and the most common open video format, MP4. They work well even if you never buy a song from Apple. And iTunes and the iPod work on Windows computers, not just Macs. So how is that closed?

It's amazing that this needs to be pointed out to people, but the Microsoft misinformation campaign is succeeding in convincing people that if you use iTunes or an iPod that all your music is locked in. Only music and videos purchased from the iTunes Music Store are locked from full and fair use (even free downloads). Competing digital music services are not Mac-compatible, so their claims of being 'open' are ridiculous. The music service that is truly 'open' is eMusic.