Hmmm doesn't really matter to me yet, but eventually it will when i upgrade to a PS3...
BD+ is essentially an extra layer of content protection that rides above the already compromised AACS encryption system. BD+'s capabilities in validating that a movie is playing in a secured system are though to be far stronger than other systems available, in that it can access and even disable hardware features (like Managed-Copy, if it was available). BD+ cannot, however, permanently alter hardware it encounters, so restrictions leveled by the system will be removed when the disc is ejected.
Fox was the most insistent of the movie studios desiring extra copy protection in next-gen DVDs. The HD-DVD group's refusal to implement a BD+ like DRM system on top of AACS was one of the primary factors in Fox choosing exclusive Blu-ray support. Now that the BD+ system is ready to go live it is expected that Fox will be making major announcements on releasing some of the studio's AAA properties on Blu-ray.