Apparently the answer depends on what part of the world you are in. If you are in Asia, the latest version is still 9.63 as of today – http://www.interactivebrokers.com.hk/en/p.php?f=programInterface&ib_entity=inst
but it is already 9.64 elsewhere
– http://www.interactivebrokers.com/en/p.php?f=programInterface&ib_entity=llc
And, the latest version is exactly the same beta version when it is still beta.