Is it possible to use Entity Framework (any version, including, and preferably 4.0) to query an SSAS cube (preferably SSAS 2008)?
Yes, now it is possible to use EF 4.0-4.1 to query SQL Server Analysis Services 2008 OLAP cubes (it is something like LINQ to MDX / SSAS). You will need to install SSAS Entity Framework Provider (tm) to enable that. You can checkout and request SSAS Entity Framework Provider here:
http://www.agiledesignllc.com/Products.htm
Disclosure: I work for Agile Design LLC - the company who offers this product.