Hey guys, I have a rampage 3 extreme and I modded the latest 1601 bios with the 11.6.0.1702 Intel sata/raid firmware.

I can confirm that raid 0 trim is working on x58.

I had to use the latest RST 12.0.0.1013 beta driver from station-drivers because I couldn't get the rapid storage utility to load on any of the others, but I would guess that any driver that supports trim would trim the drive.
http://www.station-drivers.com/page/intel%20raid.htm