IBM Cognos TM1 is a multidimensional database that my company thinks is the latest and greatest. I've been to the classes and, sure, it is nice for analysis. Of course the finance people in my company only see the Excel Add-In or Excel-like website and think "that's all I need for a data entry application!" My response is "I thought you need an OLTP solution!" which they ignore because I'm in IT.
What I see is something that has questionable integration with my preferred Microsoft development tools. I'd rather deploy a Silverlight data entry/OLTP tool. I also see that TM1 has unmanaged dll's that provide full access into the data engine. Since IBM bought TM1, I don't see a friendly future for Microsoft and TM1.
Is it completely irrational to think LinqToEntities could create an ORM to TM1? Is LinqToEntities ever used to point at a multidimensional database? What about nHibernate? I would like to say to our finance people, sure let's use TM1 and I'll use it as the backend of the data entry application that I create for you.