I highly recommend you go read Cory Doctorow’s article on Apple embedding Trusted Computing technology into their OS kernel in an attempt to prevent circumvention of DRM.
By extension, this technology can also have the result that if you are using proprietary applications, you will not be able to open files created on those programs in another piece of software even if the file format is supported.
Yep, as I previously observed, Apple is taking lessons while it sleeps with the RIAA, and their twisted lovechild is something for consumers to fear.