Anandtech has published a long article on the Mac Pro Nehalem. It is full of tests results, but also covers their adventures to replace the two 2.26 GHz processors with the 2.03 GHz versions.
During their adventures they damaged one of the processor connectors on the CPU board, which forced them to change it. These connectors are very fragile and do not accept any inaccuracy at the time of the installation of the processor. It should be noted that the replacement card cost them only $400; this should kindle hope for those which chose a mono CPU model.
In the near future, the lucky owners will be able to play at changing the processors of their machine for more faster one. Intel provides already models with 2,3 GHz and should propose some soon at 3,4 GHz in the W5590 version.
