How does Prism compare with Caliburn?
I'm starting out with these frameworks too and this is what I gather.
Caliburn has been around longer and in my opinion looks to be more mature in some ways. It supports multiple IoC containers for example. However, some of the implementations of common features done in Prism are nice too and the founder of Caliburn has even removed some features that you would then get from Prism.
Prism's big advantage is that it is officially from Microsoft and as such will probably mature to become an industry standard in some ways. They will also support other IoCs other than Unity in the future.
From my reading, it appears possible to actually use both and that is what I'm looking into. I'll post back if I have any success