I pulled down the latest KDE 4 RC1 ISO (0.7.1), burned a copy, and went around the house trying to boot it. Turns out it won't boot on old europa, but it did boot on algol (the Gateway M685).
The KDE 4 RC1 CDROM contains the latest version of Open Suse 10.3 with current updates. I was surprised that it would only boot on the notebook and not the older desktop. That's a complete reversal from past behaviours. What's more, KDE 4 RC1 booted with complete screen resolution and full multimedia. What didn't work was graphic acceleration. What also didn't work was wireless networking.
I'm not sure what to make of KDE4 at this point. I know a lot of work has gone into the internals, so it's very hard to be overly critical. But if this is a release candidate then the visual aspects are still quite rough. I also had this release's desktop lock up once, which has never occurred with any prior live CD I've booted. I'm real curious to see how this continues to evolve up until its formal release in January.