Open Radar is a web site where developers share bug reports they've filed with Apple. From the Open Radar FAQ:
... I've been frustrated that I couldn't search the Apple bug database for problems that I was having or for the status of issues that others have filed, even when my own submissions have been marked as their duplicates.
I have heard that the bug database is closed because it contains customer-sensitive information. That's understandable, but if it were possible to check a box that allowed public disclosure of our submissions, many of us would be willing to do that. - Tim Burks
Until Apple makes that available, Open Radar hosts bug reports and developer comments. Open Radar is only for discussion of publicly-known features; bug reports covered by NDA are expressly excluded.
Open Radar runs on Google App Engine, and includes an API that can be used to get a JSON dump of its entire data store. Source code is available on github. Other contributors include Dave Dribin, Joachim Bengtsson, and Chris Verwymeren.
Open Radar: using social networking to squash Apple bugs by Erica Sadun on Ars Technica, Nov. 16, 2008