I've spent some time in the last few days evaluating the two products that look more promising as a platform for the Source.zone initiative: Jotspot and Confluence.
First of all, let me say that both are cool products, made by very cool companies. And now for some comparisons.
Jotspot has some features, like forms, that could be useful. Plus, it's a hosted service, which should translate to lower activation costs, whereas Confluence is $1200 plus hosting.
On the other hand, being hosted has its disadvantages. With Confluence, I can do pretty much everything I want, on my own server, even modify it, since it comes with source code. With Jotspot, I have considerably less freedom. Moreover, Jotspot is still in beta, whereas Confluence is already at version 1.3.
All things considered, Confluence seems to have the edge, at the moment, mainly because with it I can already publish a website visible to the public, a thing that is currently not possible with Jotspot. I can also customize it much more easily.
While I'm at it, I will briefly mention XWiki, that was brought to my attention by Ludovic Dubost. From the set of its features, it looks interesting, and it's Open Source, which is not bad. I should find the time to test it too.