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.