Oracle just announced a new line of Nehalem based x86 servers and they are beasts:
Interesting to note: the x4450, my previous favorite due to being the only 2RU 4 socket Xeon I’m aware of has a new big brother- the Sun x4470. It seems they couldn’t get 4 7500 series Nehalems in 2RUs or else they realized that no one could compete with them in 3 RUs so why bother. http://www.oracle.com/us/products/servers-storage/servers/x86/sun-fire-x4470-server-077286.html
Also interesting is the 5 rack unit Sun x4800 which supports 8 Nehalem 7500 series processors, up to 64 cores, hot-swappable IO cards, 1TB of RAM and has built in NEMs (borrowing from blade tech it seems). A fully loaded server runs about 3KW at 100% utilization according to the power calculator which is more than a similarly configured (much more reliable) M5000 but in half the rack space: http://www.oracle.com/us/products/servers-storage/servers/x86/sun-fire-x4800-server-077287.html
Also interesting is widespread support for all types of SSD and Flash memory modules in this line, and the additional RAS capabilities coming to the x86 line with the new Nehalem processors.
The long and short of it for me seems to be that the machines are beasts but power hungry beasts. None of the lower power Nehalems really seem to be on the table. Until we see prices, it will be hard to tell if these are worth the pdf’s their printed on.