It means that the parameter passed is actually the class, not an instance of the class, or a variable with the same name. I don't know what he Intent object does, but it must use the class you give it in some way, probably for reflection. The thread you linked actually asks two questions: the one you ask here and also about static inner classes. I didn't see a broken link in it though.
Every class in Java has an associated instance of java.lang.Class that contains metadata about the class--its field names and types, method declarations, parent class, etc. When you see ClassName.class that is known as a class literal. (http://docs.oracle.com/javase/specs/jls/se5.0/html/expressions.html#15.8.2) It is a compile-time constant that evaluates to a reference to that class's Class object.
Well, a compile-time constant expression is something else, that does not include class literals. But a class literal does refer to something that doesn't change, and is certainly understood by the compiler at compile time.