According to different sources, Intel announced to its clients that a bug is affecting Penryn Quad Core CPUs. Currently, it remains unclear if Xeon Penryn will also be affected or only the Quad Core Extreme desktop-dedicated CPU.
The bug is reported to create a problem with the FSB under certain circumstances, and with specific chipset. The problem can not be solved unless than changing the processor design, and producing new batches.
If Xeon Penryn is also affected, it could even further delay the launch of the future revision of Mac Pro (at least by one month).
[translation by Linathael]