This is supposed to resolve the Error: Data Call Failure. Error 37: Miscellaneous Erroneously Mobile IP Setup Occurred message that often appears when connecting to the network as well as provide other miscellaneous fixes.
I have heard that updating to AKU3 could prevent you from using some of the custom WM6 ROMs—which I've been very tempted to try. I really want this phone to be stable. I've heard WM6 is much more stable than WM5, but I'm not sure I want to upgrade to an unsupported ROM. Either way, I've got to do something to get this phone to a more stable and usable state.