The new CTP of Microsoft Robotics Developer Studio implements a LINQ query syntax to define Data Contract Filters on DSS (Decentralized Software Services). I don't have a real experience on Robotics SDK, but I looked at documentation for the LINQ implementation and this is a good example of the use of LINQ in an environment unrelated to relational databases.
Looking at these examples, I thought that an interesting LINQ application is the definition of filters on subscription services just as the Robotics SDK does. This mean acquisition of data changing in real-time (ok, soft real-time...). The flexibility offered by IQueryable is great.