As you maybe know, we use Jackrabbit for some of our projects and plan to use it even more. I personally still like the idea of it and until now it did what it promised.
I resurrected another piece of software I did a few (too many) months ago in the "proof of concept" phase of Jackalope, a content repository browser.
For implementing some of the JCR specs in Jackalope, we needed a simple way to sniff the HTTP traffic jackrabbit expects (via the davex protocol). So I resurrected an old java thingie I once wrote. This may be helpful to implement the missing parts of Jackalope and can be found here https://github.com/jackalope/JavaDavexClient
We initiated a new open source project called Jackalope. Its purpose is to bring JCR via Jackrabbit to the PHP world. The Team working on it currently consists of Christian Stocker, David Buchmann, Tobias Ebnöther and of course we would welcome you too! :) We use the Apache License and are very open minded about collaborations, inputs and wishes.