Apple inserted a version of DTrace in Leopard, but as Sun's Adam Leventhal found out, they crippled it to keep it from being used with iTunes, in order to protect both content and its DRM technology.
Technically there is nothing wrong with that. As part of Solaris 10 DTrace is under the CDDL license. Apple seems within its rights under this license. Recompiling and creating a replacement library may also be mostly impossible.
Mostly impossible, course, isn't the same thing as really impossible. John Birrell says he's working on an alternate version of a Mac DTrace, with funding from Cisco.
My problem is, if Apple materially changed DTrace, why do they still call it by that name? Why not call it iDTrace?
This is all another example of how the demands of content companies are corrupting software. It's also an example of how an enterprise server program may be completely inappropriate in a commercial desktop environment.
The number of people angered by this may be miniscule, when compared to the universe of Leopard users. But we're talking here about very smart people, power users, the kind you don't like to get mad at you.