TDWI (Score 1)

For coverage on OLAP and more generally, business intelligence, visit The Data Warehousing Institute. In addition to their online articles, you can subscribe to a weekly email newsletter which provides timely info about BI and OLAP developments. If you really want to get into it, they have some hands-on courses offered fairly regularly around the US. I haven't taken any of them, but based on the course outline the OLAP course looks pretty informative and I think TDWI has a good reputation.

Finally, you might check out DM Review's website as they have some good content on data warehousing, BI and OLAP as well.