After months of waiting the new G2 bits are here for both Smartphone and Pocket PC devices!
Before installing the new bits you will need to uninstall the current build from your device (if you haven't already done so). To uninstall the old bits go to the Start Menu | Settings | Remove programs. The uninstall process may take several minutes, and does require that your device be rebooted.
The install process is the same as before, depending on if you have XP or Vista.
News source: MS Connect (pass req.)