I’ve had an email from Alexandru Toth about an open source OLAP project he’s working on. Here’s what he had to say:
I am developing an Open Source OLAP project called "Cubulus". There is a presentation material at http://cubulus.sourceforge.net/ , and an online demo at http://alxtoth.webfactional.com/ .The source code is at http://sourceforge.net/projects/cubulus/ .
In brief, Cubulus is an analytic engine + slice&dice web interface on top of relational database (MySQL at the moment) . It caches calculated cells, and is able to parse basic MDX queries. Project is in early alpha, and runs on Mac OS X, on Windows .. and on Linux too
Perhaps not ready for the enterprise just yet, but still a worthy effort and any new OLAP that supports MDX is ok with me.