You should take a look at the thread
Official Sprint ROM 3.35.651.2 - Discussion.
But the main features of this ROM from the last are:
1.Adds EV-DO Rev.A functionality for faster download and upload speeds when transmitting data wherever EV-DO Rev. A coverage is available.
2.Adds advanced GPS functionality including the software for Sprint Navigation.
3.Adds a Task Manager to the Today screen for easier access and management of Running Programs.
4.Improves Bluetooth performance including usage with Phone As Modem and wireless stereo headsets.
5.Corrects an issue where Windows Live Messenger content may be erased when the device power cycles.