Apple seeded Mac OS X 10.4.8 to Developers on Friday. A number of issues are fixed in this seed including issues with Image RAW, CoreImage, ColorSync, Rosetta, Xsan and File Manager.
The Intel version of the build is said to be 8L2122 and the PowerPC at 8L112.
An unconfirmed Digg posting claims that there are a number of other significant changes to 10.4.8 including enahnced OpenGL and Video performance, but this has not been confirmed.
It's possible this could refer to Multithreaded OpenGL which is presently only available on the Mac OS X 10.4.7 build that ships with Mac Pros.