Pretty sure it's just the CNSD-200FM update Pioneer sells. Supposed to be primarily a map update, guess they bumped the APL version with it. See http://avic411.com/index.php?/topic/28583-pioneer-2010-maps-cnsd-200fm/page__view__findpost__p__212683 for the version bumps "clams" saw when installed on their deck.
I have searched and searched (even going to look on the US, EU and AU pioneer support sites) for 4.0 firmware. I just dont see anything. Can anyone provide information on this? I thought I remember reading someplace that there was a regional specific update that was being called 4.0 and was fairly minor. But searching here has yielded nothing.