Okay, maybe you missed the part where they said 'beta'. Beta software is buggy. It will be picky, and it will have problems! You need to have patience. My suggestion first:
Those without a non-upgrade g3 or g4: DON'T EVEN BOTHER, UNLESS, you are willing to spend a lot of time and patience on this project.
Those with a g3 or g4. It will work. You need to have patience. You should strip your machine down to it's factory shipping specs. Extra HDs out, SCSI peripherals out, extra non-stock video cards out, extra RAM out, at least to the point of 128MB, speakers, USB stuff (It is notoriously unreliable with OSX B), Firewire peripherals, and all other expansion cards.
You will not be able to use USB and Firewire HDs for boot, so you definetely don't need them there during install. USB printers are not going to work very well until companies do drivers.
Install on an HFS drive. UFS drives have bugs with them. In my experience, if you use a UFS, Classic and Explorer, and various other things are caused huge difficulties. BUT. If you install on HFS, first thingyou need to do after install is boot into OS X, then into OS 9, and then to OS X again, and make sure the boot works all three times. If it doesn't, you've got a problem. After you boot into OS9 the first time, you may lose your ability to boot into OS X off HFS. In this case, you may have no other choice but to stick strictly to OS X, not ever booting to 9 (as I am doing), or to install on a UFS, where this particular problem doesn't exist, but the above involving Classic and IE are there.
If I think of anything else, I'll mention it. The simple fact with OS X, is that it is in BETA right now, and there are problems. It's what happens. It's why companies very rarely release software as a PUBLIC beta, and Apple is the first major company to release an OPERATING SYSTEM as public before final. Linux doesn't count.
PowerMac G4 DP: 2x450MHz, 30GB, 128MB, DVD, 10/100/1000Mbps, Mac OS 9.0.4, Mac OS X 10.0.1, Mac OS 9.1
PowerBook G3 (Wallstreet): 266MHz, 4GB HD, 128MB, 20X CD, 10Mbps, Mac OS X 10.0.1, Mac OS 9.1