Q: What is the latest official bios revision?
A: The latest non beta version of the a7a bios is the rev. 1006, and you can download it here (local). The update bring a major compatibility with the Palomino CPUs and grant a wide range for overclock.
Asus say that the 1006 version is like the 1006.01 beta version and report on his site this:

Fix CPU frequency not shown correctly if CPU is faster than 1.3GHz.