The seed is said to contain dozens of minor bug fixes and performance improvements in these areas:
Address Book, AppleScript, AppleScriptObjC, ATS, ColorSync, Component Manager, Core Animation, Core Audio, Core Chinese Engine, Core Data, Core Graphics, Core Text, File Manager, Garbage Collection, Graphic drivers, Help Viewer, ImageKit, IOHIDFamily, Networking, NS Image, OpenCL, OpenGL, OSA, QT Kit, Speech Recognition, Sync Services, and Xtype.
The seed notes reportedly include a caution that there is a known issue with optical drives: that they may not be recognized and the eject key may not eject the media, and that DVD Player may hang. As a result, not all developers may choose to install this build.
Note: Mac OS X 10.6.1 was released September 10.