Here is the full change-log from T-Mobile :
* Wi-Fi Calling for Android new!
* Resolves device freeze and unexpected power-off issues
* Improves data connection reliability
* Optimizes radio recovery
The software update version is 1.22.531.8 and it will be automatically downloaded on your device. Users will be prompted to install the update after it has been downloaded. The T-Mobile G2 sports a pop-out QWERTY based keyboard with a 3.7-inch screen. The handset runs on stock Android 2.2 with no HTC Sense UI on top of it.
Hopefully, we will see many more Android phones getting the Wi-Fi calling capability in the future.