Update:

Following instructions I found elsewhere, I booted from my DVD, mounted my HD root file system and deleted the AppleEFIRuntime driver. Upon reboot, I got another kernel panic this time from AppleIntelCPUPowerManagement. I noted in some forum that the recommended action was to also delete THAT kext. So I did that and rebooted. This time, I get the old "still waiting for root device". Not sure how to proceed now (remember, I had 10.5.2 Rev 2 working fine on this machine until I installed the CHUD tools as part of the iPhone SDK).

Prior to getting this release working the first time, I had the "still waiting for root device" problem -- but the root device in that case was the DVD drive. I got past that by adding a new version of a couple kexts that were associated with fixing SB600 (SouthBridge ATI chipset) problems. I checked, and I still do have both of those kexts in my /System/Library/Extensions directory, so that isn't the problem.

Anyone have any ideas?