Corsair yesterday announced its production of its fastest memory modules yet, rated as XMS4400. These modules are spec'ed to run at 550MHz DDR frequencies (1100MHz FSB) at 3-4-4-8 latency timings at 2.75Vdimm. The modules will be available as 2 X 256MB or 2 X 512MB matched sticks, & were tested on the Asus P4C800-E, i875P chipset boards for stability & timings. There has not been a "Pro" line of these sticks announced..... yet.

Full press release here. Product page here.