I've been waiting so long for this update:
This upgrades my HD2's from ROM Version: 1.66.707.1 to the latest ROM version of 3.14.707.3 and the improvemets are as follow:
1.Keeping in touch has always been very important, and this update delivers fast and reliable SMS messaging.
2.Support for the new Extended Battery accessory.
Before you proceed, please confirm that this software upgrade is a newer version than what is currently installed on your device. If it is the same version and your device is operating normally, there is no need to reinstall the software.
To check what version is installed on your device, click Start > Settings > System tab > Device Information > Version tab, and note the ROM version, CPU, and Radio version.
I'm in the process of downloading the ROM and i shall update on the changes after testing it.