DailyTech has a story up about the upcoming six core Dunnington Xeon CPU, which is a replacement for the fairly recent Tigerton Xeon CPU. This new chip is pin and chipset compatible with the Tigerton Xeon, so it should work just fine with a Dell PowerEdge R900 server when it is released during the second half of 2008.
The CPU should absolutely smoke with an OLTP workload with SQL Server 2005 or 2008. SQL Server loves large L2 and L3 caches, and it runs very well on the 45nm Penryn based architecture. We have been doing quite a bit of testing with the February CTP of Katmai on a single, quad-core Xeon 5450, with very good results.
CPU-Z Shot of 2.83GHz Xeon 5450 "Harpertown"
Glenn Berry's SQL Server Performance 
http://www.batteryfast.com/sony/pcga-bpz51.htm Sony pcga-bpz51 battery http://www.batteryfast.com/sony/pcga-bpz51a.htm Sony pcga-bpz51a battery http://www.batteryfast.com/sony/pcga-bpz52.htm Sony pcga-bpz52 battery http://www.batteryfast.com/sony/vgp-bpl5a.htm Sony vgp-bpl5a battery http://www.batteryfast.com/sony/vgp-bps5.htm Sony vgp-bps5 battery http://www.batteryfast.com/sony/vgp-bps5a.htm Sony vgp-bps5a battery http://www.batteryfast.com/toshiba/pa3123u-1brs.htm Toshiba pa3123u-1brs battery http://www.batteryfast.com/toshiba/pa3178u-1bas.htm Toshiba pa3178u-1bas battery http://www.batteryfast.com/toshiba/pa3178u-1brs.htm Toshiba pa3178u-1brs battery http://www.batteryfast.com/toshiba/pa3211u-1bas.htm Toshiba pa3211u-1bas battery http://www.batteryfast.com/toshiba/pa3211u-1brs.htm Toshiba pa3211u-1brs battery http://www.batteryfast.com/toshiba/pa3479u-1brs.htm Toshiba pa3479u-1brs battery http://www.batteryfast.com/toshiba/pa3480u-1brs.htm Toshiba pa3480u-1brs battery http://www.batteryfast.com/toshiba/pa3591u-1bas.htm Toshiba pa3591u-1bas battery http://www.batteryfast.com/toshiba/pa3634u-1bas.htm Toshiba pa3634u-1bas battery http://www.batteryfast.com/toshiba/pa3635u-1brm.htm Toshiba pa3635u-1brm battery http://www.batteryfast.com/toshiba/pa3638u-1bap.htm Toshiba pa3638u-1bap battery http://www.batteryfast.com/toshiba/pabas117.htm Toshiba pabas117 battery http://www.batteryfast.com/toshiba/pabas118.htm Toshiba pabas118 battery http://www.batteryfast.com/acer/batsqu410.htm acer batsqu410 battery http://www.batteryfast.com/acer/qc145.htm acer qc145 battery http://www.batteryfast.com/acer/sq-1100.htm acer sq-1100 battery http://www.batteryfast.com/acer/sq-2100.htm acer sq-2100 battery http://www.batteryfast.com/acer/squ-202.htm acer squ-202 battery http://www.batteryfast.com/acer/squ-405.htm acer squ-405 battery http://www.batteryfast.com/acer/squ-406.htm acer squ-406 battery http://www.batteryfast.com/acer/squ-410.htm acer squ-410 battery http://www.batteryfast.com/dell/inspiron-1420.htm dell inspiron 1420 battery http://www.batteryfast.com/dell/vostro-1400.htm dell vostro 1400 battery http://www.batteryfast.com/mitac/bp-8089.htm mitac bp-8089 battery http://www.batteryfast.com/mitac/bp-8389.htm mitac bp-8389 battery http://www.batteryfast.com/sony/vgp-bpl9.htm sony vgp-bpl9 battery http://www.batteryfast.com/sony/vgp-bps10.htm sony vgp-bps10 battery http://www.batteryfast.com/sony/vgp-bps8.htm sony vgp-bps8 battery http://www.batteryfast.com/sony/vgp-bps8a.htm sony vgp-bps8a battery http://www.batteryfast.com/sony/vgp-bps9.htm sony vgp-bps9 battery http://www.batteryfast.com/toshiba/pa3369u-1bas.htm toshiba pa3369u-1bas battery http://www.batteryfast.com/toshiba/pa3369u-1brs.htm toshiba pa3369u-1brs battery