I worked with Microsoft on this one and they identified the problem. The full discussion of the problem can be found on their forum here: http://social.msdn.microsoft.com/Forums/en-US/adodotnetdataservices/thread/fcdaca20-73ea-4abb-b70b-981fe2728351/
Basically, I'm trying to use NHibernate.Linq as the provider for ADO.NET Data Services (now WCF Data Services) with an entity model for a blog. ADO.NET Data Services generates the correct metadata, shows the entities declared on an NHibernateContext-subclass, and can show the first level of entities. The problem occurs when trying to follow relationships. For example, when following a relationship between a Post entity and the Comment child entities. NHibernate.Linq, according to Microsoft, does not handle the where clause correctly and returns incorrect results.