ThinkSecret posts some more screenshots from the latest build of Mac OS X 10.5 Leopard (9A283).
Meanwhile, Apple posted a Leopard Technology Overview document for developers. Apple details several features for Leopard which are drawing some attention:
Resolution Independence
In Leopard, the system, including the Carbon and Cocoa frameworks, will be able to draw user interface elements using a scale factor. This will let the user interface maintain the same physical size while gaining resolution and crispness from high dpi displays.
OpenGL Improvements
Leopard also provides a dramatic increase in OpenGL performance by offloading CPU-based processing onto another thread which can then run on a separate CPU core feeding the GPU. This can increase, or in some cases, even double the performance of OpenGL-based applications.
QuickTime Improvements
QuickTimes plumbing is receiving significant upgrades in Leopard. There have been significant enhancements in handling the H.264 encoding. Also, transparent alpha layers, an optional part of the H.264 specification, are now supported in H.264-based QuickTime movies. And finally, QuickTime supports 64-bit.
OpenGL Improvements were previously described in August after WWDC. This new Multithreaded OpenGL has already been incorporated in the Mac Pro's version of Mac OS X 10.4.8.