Here's some fascinating video from Yosemite Park, showing and discussing the process of rock falls:
Geologists discuss the rock falls, and their effect on park visitors, and there's some great video from a park visitor.
The video's a granite-lover's dream, with obligatory spectacular views of Yosemite as well.
I'm feeling less inclined to scramble in the talus looking for pikas than I might once have been.
Does the information in this video affect how you would use Yosemite, or whether you would visit the park or similar areas?