You aren't looking back far enough, sir!
Nehalem for servers launched in Nov. 2008. When did Lynnfield launch, again? That's right -- almost a year later, in September of 2009 🙂
The reason being Nehalem removed the major drawback of Intel Xeons at that time which used FSB and brought a point to point interconnect called QuickPath. Moreover Nehalem launched on a mature 45nm process a year after Penryn desktop launched. Different times and different situations. Lets see if Intel repeat it. Maybe their next grounds up new architecture which might come next decade may launch on server/HEDT.