Step 1: Don't boot off the DVD. It failed to actually boot (getting stuck at some "select your device" dialog)
Step 2: Install XP
Step 3: Insert beta DVD, click Install Now
Step 4: Do a clean install
Worked for me, I could even install BootCamp 2.1 off of my 10.5.4 install disc and had all the drivers out of the box *except* for the Radeon drivers. I downloaded Mobility Modder from DriverHeaven and Catalyst 8.12, and let MM go to work. Driver installed perfect after that.
Everything seems to work, from AppleTime service (because OS X uses GMT and adds/subtracts and Windows stores local time in CMOS) to the Boot Camp control panel to all the keyboard stuff like brightness/volume controls on the F keys, as well as eject.
Even though you need a key from MS to activate, the direct download links install sans key and give you 30 days to activate.
Try to keep this thread on the task of installing Win7 beta on your Mac, and NOT a discussion of how MAC SUXXX AND WINDOWZ ROXORZ.
"And and if you start to bleed, stop wiping." -whm1974