In previous versions of java, rethrowing an exception was treated as throwing the type of the catch parameter.
For example:
public static void test()
I believe I saw a tweet from Josh Bloch saying that the "final" restriction had been lifted late on. I'll see if I can find a post about it, but I suspect it's just that any "early" documentation you read is now inaccurate.
EDIT: I can't find the exact "it's changed" post, but the Java 7 documentation states shows an example with it not being final. It talks about exception variables being implicitly final when a catch block declares more than one type, but that's slightly separate.
EDIT: I've now found the source of my confusion, but it's an internal mailing list post :( Anyway, it doesn't have to be declared as final, but I believe the compiler treats it as implicitly final - just like in the multi-catch scenario.