MP2,1 was also unusual as Apple released before the official Intel release. They effectively got Intel's whole supply of the first three months.
Some people said that Apple was very keen to bring 8 cores to the market because there was massive criticism that MP1,1 did not justify the Intel switch by a sufficiently big performance advantage over the PPC Quad. By topping that with an Octad Apple silenced the criticism.
I also read here on MacRumors that the initial X5365 chips were proto or engineering samples, that used higher voltage to run 3,0 GHz. That sounds incredible when you look at Apple's extremely conservative clocking policies of their 2008 and 2009 models. The regular X5365 runs on 130 W TDP. The original Apple chips ran on 150 W TDP some claim. Perhaps Steve Jobs had an open ticket for a 3,0 GHz computer from his 2003 key note. 😉