we can also see the version number in this screen from MeriStation
http://www.armaholic.com/datas/users/4-arma2_preview_meristation_april_42.jpg
same version
but honestly, i dont see why some of you are so wound up over this preview version. its also obvious that all the previewers a playing on the easies settings. look at all the markers and aids on screen. sure, the AI are no match for the human players, and probably for a long time, never will (on equal terms that is). but even core AI does not change from ArmA1, even the addition of non-forward movement and centimeter precision will increase the AIs combat efficiency tremendously.
also remember that BIS has to code AI that will also make it appealing enough for the general public. just imagine the reviews and feedback if the AI had as much common sence as a normal human. a small fire fight would last for hours and hours against even a few foes. sure most of us crazy fools who post on this forum would love that (me included), the general public would not. lets face it, hiding behind a barrier for an hour hearing shots nearby, not being able to move or shoot can get very very boring if you are not in the right mind set