You mean, from a collection of customers, select all customers which have 10 orders or more?
No, that's currently not possible directly. The filtering in-memory is done by interpreting a predicate expression based on an entity: the predicate expression either gives true or false. As the filtering system uses Predicate based classes, it's possible to write a predicateclass which does this kind of filtering for you, however it's not build in.
What you can do is add a property to Customer, which represents the Count of the OrdersCollection. You then can filter on that property.