I finally got my mitts on BeOS for PowerMac the other day. So I ran over to work, and tried it out. I'm impressed. Smooth installation, and very snappy OS.
One of the cool features, that's even a little bit jaw-dropping when you see it is that you can do live dragging of a window while it's animating!
There are obviously some rough edges yet, but it looks like the start of a very good OS for handling bit slinging (video editing, sound editing, etc..)
Right now this release is missing support for video depths other than 8-bit, and the interface take a little getting used to.
Of course they need high level services like QuickTime, and they need an application base, but if they can manage that, they've got a winner.
Oh yeah -- I was running on a PowerWave 132 (PPC 604), and the speed was quite good.