OLAP?

I think this counts as a newbie question, or blue sky speculation. I've been reading about OLAP (On Line Analytical Processing) - for the uninitiated this is a different way of looking at data than relational databases. It appears that RDBMS are not at all good for managing and extracting information from multidimensional data. So, I wonder if there is such a thing as an OLAP engine that could be (or has been) plugged into PHP? A white paper on OLAP: http://www.pilotsw.com/olap/olap.htm - I found it on Altavista so this doesn't count as a recommendation for anything. But I learned a lot from the paper. G