BB OS 4.5
VZW made it available for about 3 hours then pulled it with no explanation ... but once that releases in full i dont see why Sprint wouldnt be too far behind within the CDMA realm.
Whatever the case may be i would say be very cautious with uploading any 4.5 from other carriers (this can be done over at blackberryforums.com). I have heard some horror stories and know the grief that is caused to reload a new berry.
Back to patiently waiting.