How should I submit bug reports and feature requests?
Apple offers a feedback site where both bug reports and feature requests can be submitted by anyone. Be sure to describe the issue or feature as clearly and concisely as possible. 

Developers should use Apple Bug Reporter. If you carefully describe the issue including step by step instructions for reproducing the problem, they tend to get attention and fixed. You'll need an ADC (Apple Developer Connection) login to use the bug reporting system. Be sure to upload the System Profiler report, as well as any crash logs which may be relevant.