High Definition Content Protection (HDCP)—you can't live with it, but you practically can't buy an HD-capable device anymore without it. While HDCP is typically used in devices like Blu-ray players, HDTVs, HDMI-enabled notebooks, and even the Apple TV in order to keep DRMed content encrypted between points A and B, it appears that Apple's new aluminum MacBook (and presumably the MacBook Pro) are using it to protect iTunes Store media as well.

The technology in Apple's MacBooks that prevents a seemingly arbitrary collection of iTunes Store files from being played on HDCP non-compliant devices is perhaps more accurately called DPCP, or DisplayPort Content Protection.

Source:→ Ars Technica