I don’t know what Prism refers to, and I’m not sure precisely what you mean by “a windows cluster driving each screen”. So please forgive me if I answer your question naively.
Panda is actively used within Disney to drive a CAVE environment. I don’t know much about the architecture in that system, but they have multiple PC’s all showing different views into the same scene, each driving a different projector. To make this work requires starting up a different Panda process on each PC, loading up the same scene into each one, and ensuring that all the cameras and animations etc. are in sync. There are a handful of tools in direct/src/directd and direct/src/directdServer that provide support for synchronizing different Panda processes in this way–the tools provide mechanisms to send commands between processes, but you have to write the glue code.
If, of course, you can drive all of your rendering from a single PC, it’s much easier and Panda can do it without blinking.
One driving computer is certainly simpler, although the downside is that one CPU has to process lots of viewpoints and can become a bottleneck. This may or may not be a problem based on the nature of your scenes; it’s probably in any case be the easiest way to get started.
In the Prism case, how do you control which projector a window opens onto? Is there one virtual desktop with each projector mapped into a particular region? If so, it’s easy to open a number of windows, one for each projector region; or even to open one large window (if this works in this model) covering the entire desktop, with a different DisplayRegion for each projector region. Not sure which approach will be lower overhead in your situation; you can try them both.
I don’t have any specific examples of doing this for a CAVE, but there are examples in the forums of opening multiple windows and/or multiple DisplayRegions.