Software version is Lumia 800 (1600.2487.8107.12070) and it promises better battery performance and and power management. It was originally scheduled for 18 April, but they managed to push it a little bit But don't be too excited Yet, read this:
But before you get all excited and reach out for that cable to connect your Lumia 800 to your Mac or PC, there’s just one more thing to know: the update will not span the globe all at once. It will be queued up over 4 weeks, beginning today (28 March) for the first batch. Subsequent phased updates will be on 4, 11 and 18 April.
Read whole info here.