It looks like the cat-and-mouse game of DRM exploits is starting to inflict some collateral damage -- the DTrace debugging tool built into Leopard is apparently locked out of iTunes and any other app that opts-out. Reasons aren't clear, but it sure looks like Apple is trying to keep interested parties from seeing the inner workings of FairPlay and other DRM-enabled apps -- which probably makes the RIAA happy, but makes it harder for devs to get work done.

In the words of one DTrace developer, the lockout is "antithetical to the notion of systemic tracing, antithetical to the goals of DTrace, and antithetical to the spirit of open source."

Source- http://www.engadget.com/2008/01/23/apple-crippling-os-x-debugging-tool-to-protect-itunes-drm/